-^     it; 


BXCHANGE 

OCT  27  192: 


Flour  Strength  as  Influenced  by  the 
Addition  of  Diastatic  Ferments 


f 


A  THESIS  SUBMITTED  TO  THE  FACULTY  OF  THE  GRADUATE 
SCHOOL  OF  THE  UNIVERSITY  OF  MINNESOTA 


By 

FERDINAND  A.  COLLATZ,  B.  S.,  M.  S. 

IN  PARTIAL  FULFILLMENT  OF  tHE  REQUIREMENTS  FOR 
THE  DEGREE  OF  DOCTOR  OF     PHILOSOPHY 


August,  1922 
Chicago,  III. 


Flour  Strength  as  Influenced  by  the 
Addition  of  Diastatic  Ferments 


A  THESIS  SUBMITTED  TO  THE  FACULTY  OF  THE  GRADUATE 
SCHOOL  OF  THE  UNIVERSITY  OF  MINNESOTA 

By 

FERDINAND  A.  COLLATZ,  B.  S,  M.  S. 

IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS  FOR 
THE  DEGREE  OF  DOCTOR  OF      PHILOSOPHY 


August,  1922 
Chicago,  III. 


TABLE  OF  CONTENTS 

Page 

I.  Introduction :     Definition  of  flour  strength 5 

A.   Historical    6 

1.  The  proteins  of  wheat  flour  and   their  physical   relation   to   flour 

strength    i  •  •   6 

2.  The    carbohydrates    of    wheat    flour    and    their    relation    to    flour 

strength •  . .  .  9 

3.  Historical  review  of  the  diastatic  enzymes 13 

a.  The  Iodine  method  for  the  estimation  of  diastatic  activity ..  .15 

b.  Copper  reduction  method  for   the  determination  of  reducing 

sugars  formed  by  the  action  of  diastase 16 

c.  Influence  of  temperature  on  diastatic  activity 17 

d.  Influence  of  acids,  bases  and  salts  on  diastatic  activity 17 

4.  Effects  of  proteolytic  enzymes    18 

5.  Hydrogen  ion  concentration    19 

6.  Viscosity   : 19 

II.  Experimental • 20 

A.  The  problem 20 

B.  Material • 20 

1.  Description  of  materials  used  in  these  studies 20 

a.  Analysis  of  wheat  flours 21 

b.  Analysis  of  malt  flour 21 

c.  Analysis    of   malt   extract 21 

C.  The   methods 22 

1.  Determination  of  diastatic  activity 22 

2.  Determination  of  proteolytic  activity 23 

3.  Determination  of  gas  producing  capacity  of  flour 24 

4.  Baking   tests    24 

D.  Influence  of  varying  conditions  on  diastatic  activity 25 

1.  Determination  of  the  optimum  pH  for  the  amylase  of  malt  flour.. 25 

2.  Influence  of  time  of  digestion  on  the   diastatic  activity  of  malt 

flour   26 

3.  Effect  of  temperature  upon  diastatic  activity .28 

4.  Effect   of   concentration   of   diastase    on   hydrolysis    of   starch    in 

wheat  flour    30 

5.  Effect  of  increasing  amounts   of  malt  flour  when   digested   with 

a  constant  quantity  of  wheat  flour .^. . .  .31 

6.  Production  of  reducing  sugars  in  the  dough  during  fermentation. 32 

7.  Determination  of  proteolytic  activity  as  measured  by  the  fall  in 

viscosity  of  flour-water  suspensions  when  digested  with  diastatic 
preparations •  . .  .41 

8.  Gas  production  capacity  of  wheat  flour  in  relation  to  strength.. 47 

9.  Change  in  hydrogen  ion  concentration  of  fermenting  dough 48 

10.  Baking  data   48 

III.  Discussion 54 

1.  Changes  in  pH,  temperature  and  concentration  and  their  effects 

upon  the  activity  of  diastases  contained  in  malt  flour 54 

2.  Effect  of  diastatic  enzymes  upon  starch  of  different  flours 55 

3.  Production  of  reducing  sugars  in  the  panary  fermentation  of  bread 

and  the  effects  of  diastases  added  to  the  dough 56 

4.  Effect    of    proteolytic    enzymes    contained    in    malt    preparations 

upon  the  viscosity  of  strong  and  weak  flours,  following  the  addi- 
tion of  various  amounts  of  lactic  acid 58 

5.  Gas  producing  capacities  of  strong  and  weak  flours  and  the  effect 

of  added  malt  extract  upon  them 59 

6.  Changes  in  hydrogen  ion   concentration  taking  place  during  the 

fermentation    of    the    dough 60 

7.  Effect  of  malt  flour  and  malt  extract  upon  the  baking  value  of  flour.60 

IV.  Summary 62 

V.  Literature  cited   63 


FLOUR  STRENGTH  AS  INFLUENCED  BY  THE 
ADDITION  OF  DIASTATIC  FERMENTS 

By  Ferdinand  A.  Collatz 

I.     INTRODUCTION. 

The  baking  strength  of  flour  has  received  a  great  deal  of  attention 
by  scientific  workers  in  the  last  twenty-five  years,  due  primarily  to 
the  economic  importance  of  bread.  A  number  of  factors  have  been 
thoroughly  investigated,  in  their  relation  to  baking  strength,  in  order 
to  draw  some  conclusions  as  to  why  some  flours  give  a  large,  light,  pal- 
atable loaf  of  bread  and  others  an  inferior  loaf.  Certain  factors  which 
have  been  investigated  in  their  relation  to  baking  strength  are  total 
nitrogen,  ratio  of  water-soluble  nitrogen  to  total  nitrogen,  chemical 
composition  of  the  individual  proteins,  total  gluten,  total  gliadin,  ratio 
of  gliadin  to  glutenin,  ratio  of  gliadin  to  total  nitrogen,  ratio  of  wet 
to  dry  gluten,  eflFect  of  electrolytes,  hydrogen-ion  concentration,  total 
amount  of  gas  evolved  during  fermentation,  and  the  effects  of  diastatic 
and  proteolytic  enzymes  of  the  flour. 

Flours  which  bake  out  well  have  been  given  the  arbitrary  term  of 
strong  flours  while  the  others  are  termed  weak.  Naturally  a  great 
number  of  definitions  of  strength  have  found  their  way  into  the  litera- 
ture, but  the  definition  that  has  been  most  generally  accepted  is  that  of 
Humphries  and  Biffin  (1907),  who  state  that  "a  strong  wheat  is  one 
which  yields  flour  capable  of  making  large,  well-piled  loaves."  Flours 
which  do  not  measure  up  to  this  empirical  standard  are  classed  as 
weak.  This  definition  indicates  that  strength  in  flour  is  more  desir- 
able than  weakness  for  the  >baking  of  bread.  Wood  (1907),  has  called 
attention  to  two  factors  in  strength,  namely,  size  and  shape  of  the  loaf. 
This  has  stimulated  a  great  deal  of  research  by  Ford  and  Guthrie 
(1908),  Baker  and  Hulton  (1908),  on  the  diastatic  and  proteolytic  en- 
zymes in  wheat  flour,  and  also  by  Upson  and  Calvin  (1915)  (1916), 
Gortner  and  Doherty  (1918),  and  Sharp  and  Gortner  (1922),  on  the 
colloidal  properties  of  wheat  gluten  as  affecting  flour  strength.  To- 
day we  must  recognize  three  groups  of  factors  dealing  with  strength 
or  weakness  in  flour.  According  to  Sharp  and  Gortner  (1922).  we 
have  "at  least  three  classes  of  weak  flour,  i.  e.,  (1)  weakness  due  to 
an  adequate  quantity  of  gluten  but  of  inferior  quality,  (2)  weakness 
due  to  an  inadequate  quantity  of  a  good  quality  gluten  and  (3)  weak- 
ness due  to  factors  influencing  yeast  activity." 


\  s 


*  *. 


HISTORICAL. 

Not  until  Osborn  and  Voorhees  (1893)  (1894),  established  the  com- 
position and  properties  of  the  wheat  proteins  was  any  great  advance 
made  in  regard  to  flour  strength,  and  naturally  attention  was  then  di- 
rected to  the  two  main  proteins,  gliadin  and  glutenin.  Fluerent  (1896) 
asserted  that  flour  strength  depended  upon  the  proportions  of  gliadin 
to  glutenin,  the  ratio  of  75  percent  to  25  percent  or  3  to  1  being  most 
nearly  ideal.  Snyder  (1899)  came  to  similar  conclusions  but  stated 
that  the  ideal  ratio  was  65  percent  gliadin  and  35  percent  glutenin. 
In  a  later  publication  Snyder  (1901)  claims  quality  rather  than  quan- 
tity of  protein  is  of  the  greater  importance.  Shutt  (1904)  (1907) 
points  out  that  after  several  years  of  research  '*it  appears  extremely 
doubtful  if  the  gliadin  number  (percentage  of  albuminoids  in  the  form 
of  gliadin)  constitutes  a  factor  that  can  be  correlated  with  bread  mak- 
ing values  as  obtained  by  baking  trials."  These  conclusions  are  again 
verified  in  a  later  report.  Thatcher's  (1907)  results  show  that  no  single 
factor  or  group  of  chemical  tests  which  he  tried  give  results  from 
which  the  comparative  baking  qualities  of  flour  can  be  determined. 
Blish  (1915)  states  that  the  gliadin-glutenin  ratio  is  much  more  con- 
stant in  flours  of  different  baking  strength  than  has  heretofore  been 
supposed.  Blish  found,  after  careful  investigation,  that  the  individual 
proteins  of  weak  and  strong  flours  are  chemically  identical. 

The  soluble  proteins  of  flour  have  also  had  their  share  of  investiga- 
tions as  to  their  relation  to  baking  strength.  Snyder  (1897),  Bremer 
(1907),  Wood  (1907)  and  others  have  found  no  relation  of  baking 
strength  to  the  amounts  of  water  soluble  proteins. 

Quite  recently  Martin  (1920)  has  attempted  to  correlate  certain 
properties  of  flours  with  baking  strength.  He  finds  "for  flours  having 
a  satisfactory  gas  producing  capacity,  bakers'  marks,  gas  retaining  ca- 
pacity, and  amended  gliadin  content  are  closely  related,  and  it  is  con- 
sidered that  the  estimation  of  the  gas  producing  capacity  will  indicate 
the  strength  of  the  flour." 

Martin's  ''amended  gliadin"  content  is  the  diflference  in  protein 
(Nx5.7)  between  the  amounts  extracted  by  50  percent  alcohol  and 
that  extracted  by  water  acting  for  three  hours  at  24-25°.  Sharp  and 
Gortner  (1922)  find  that  "amended  gliadin"  values  were  not  correlated 
with  the  strength  of  the  flours  with  which  they  worked. 

The  Proteins  of  Wheat  Flour  and  Their  Physical  Relation  to  Flour 

Strength. 

As  far  as  we  know,  all  proteins  belong  to  that  class  of  colloids  known 
as  emulsoids  and  more  recently  termed  "hydrophylic  colloids."  As 
the  latter  term  suggests,  this  class  of  colloids  has  a  great  affinity  for 

6 


water,  which,  however,  can  be  modified  to  a  great  extent  by  the  addi- 
tion of  acids,  bases  and  salts  to  the  dispersion  medium. 

Hofmeister  was  one  of  the  first  to  investigate  the  swelling  of  pro- 
teins. He  found  that  in  solutions  of  sulphates,  tartrates,  acetates, 
alcohol  and  cane  sugar,  gelatin-plates  take  up  less  water  than  they  do 
when  immersed  in  distilled  water,  while  in  solutions  of  potassium,  so- 
dium or  ammonium  chlorides,  sodium  chlorate,  sodium  nitrate  and  so- 
dium bromide,  they  take  up  more  water  than  they  do  when  immersed 
in  distilled  water.  Hofmeister's  work  has  been  enlarged  upon  by  oth- 
ers, notably  Pauli  (1899)  (1902)  (1903)  (1905)  (1906)  and  Fischer 
(1915)   (1918). 

Wood  (1907)  and  Wood  and  Hardy  (1908)  have  demonstrated 
wheat  gluten  to  be  an  emulsoid  colloid  and  as  has  already  been  noted 
the  water-holding  capacity  of  hydrophylic  colloids  can  be  altered  to  a 
marked  degree  by  the  addition  of  electrolytes.  Acids  and  bases  cause 
imbibition  up  to  a  certain  point,  while  neutral  salts  tend  to  inhibit  the 
imbibition  of  water. 

It  appears  that  Wood  (1907)  was  the  first  to  call  attention  to  the 
physical  properties  of  the  proteins  in  wheat  flours  rather  than  the 
chemical  differences  in  relation  to  flour  strength.  He  investigated  the 
possible  chemical  differences  between  the  glutenin  and  the  gliadin  of 
these  two  classes  of  flours.  From  this  he  concludes  that  strength 
(particularly  the  shape  of  the  loaf)  is  closely  related  to  the  physical 
state  of  the  gluten,  which  in  turn  is  affected  by  the  presence  of  elec- 
trolytes. 

Wood,  and  Wood  and  Hardy  determined  the  effects  of  acids,  with 
and  without  salts,  by  suspending  bits  of  gluten  from  glass  rods  in  the 
liquid  to  be  investigated.  They  found  that  dispersion  of  the  gluten 
starts  immediately  when  immersed  even  in  the  lowest  concentration 
of  acid,  and  dispersion  increased  with  increase  in  concentration  within 
certain  limits.  This  holds  good  for  sulphuric,  phosphoric  and  oxalic 
acids,  but  not  for  hydrochloric.  When  the  concentration  of  the  latter 
exceeded  N/30  the  dispersion  began  to  decrease  until  at  a  concentra- 
tion of  N/12  the  gluten  was  more  elastic  and  coherent  than  in  its 
original  condition.  The  addition  of  salts  decreases  dispersion  in  all 
cases  and  such  amounts  of  salts  can  be  added  which  will  prevent  the 
dispersion  of  the  gluten.  From  this  Wood  suggests  "that  the  varia- 
tion in  coherence,  elasticity  and  water  content,  observed  in  gluten  ex- 
tracted from  different  flours,  is  due  to  varying  cancentrations  of  acids 
and  salts  in  the  natural  surroundings  of  the  gluten,  rather  than  to  any 
intrinsic  difference  in  the  composition  of  the  glutens  themselves." 
Wood  thinks  that  the  direct  addition  of  acids  or  salts  to  the  flour,  in 
order  to  strengthen  it,  is  impractical  as  they  would  have  to  be  in  con- 

7 


tact  for  forty-eight  hours  before  baking.  He  found  that  this  was  the 
time  required  for  the  gluten  to  come  into  equilibrium  with  its  sur- 
roundings. He,  therefore,  advocates  the  blending  of  such  flours  which 
will  supply  each  flour's  requirements  in  this  respect. 

In  a  later  paper  Wood  and  Hardy  (1908)  take  up  the  theoretical 
discussion  of  the  effects  of  acids,  alkalis,  and  salts  upon  gluten. 

Upson  and  Calvin  were  the  next  to  study  the  colloidal  swelling  of 
gluten.  They  atacked  the  problem  in  a  slightly  different  manner, 
washing  out  the  gluten  with  distilled  water  and  pressing  it  out  into 
thin  layers.  They  next  cut  out  discs  of  uniform  size  and  weighed 
them  immediately.  The  discs  are  then  immersed  in  acid  and  acid-salt 
solutions  of  varying  concentrations  for  a  definite  period  of  time  when 
they  are  taken  out,  drained  and  weighed.  They  find  that  "flours  con- 
taining acids  and  salts  in  such  combinations  as  to  favor  water  absorp- 
tion will  behave  as  weak  flours,  whereas  those  containing  acids  and 
salts  in  such  combinations  as  inhibit  water  absorption  will  behave  as 
strong  flours."     Their  conclusions  are  very  similar  to  those  of  Wood. 

Gortner  and  Doherty  were  the  next  to  investigate  the  colloidal  prop- 
erties of  wheat  flour  gluten.  Their  method  of  attack  was  like  that  of 
Upson  and  Calvin,  in  that  they  recorded  the  increase  in  imbibition  by 
weighing  discs  of  gluten  after  immersion  in  acid  and  acid-salt  solutions 
of  various  concentrations.  They  worked  with  five  different  flours, 
namely  a  high  grade  patent  flour  milled  from  hard  spring  wheat,  a 
clear  flour  and  three  typically  soft  flours  milled  from  Oregon  wheat. 
Their  results  show  that  the  gluten  from  a  weak  flour  has  a  much  low- 
er rate  of  imbibition  and  a  much  lower  hydration  capacity  than  the 
gluten  from  a  strong  flour ;  also  that  inorganic  salts  when  added  to  an 
acid  solution  lower  the  relative  imbibition  of  gluten  placed  in  such 
solutions.  Glutens  from  the  different  flours  react  differently  to  the 
addition  of  inorganic  salts.  This  leads  them  to  believe  "that  a  weak 
gluten  does  not  owe  its  'weakness'  nor  its  imbibition  curve  its  'flat- 
ness,' to  either  the  acid  or  the  salt  content  of  the  flour  from  which  it 
is  derived,  'but  rather  to  the  fact  that  a  weak  gluten  has  inherently  in- 
ferior colloidal  properties." 

In  1918  and  1919,  a  series  of  articles  dealing  with  the  physical  prop- 
erties of  wheat  flours  were  published  by  Henderson  and  his  co-work- 
ers. Inasmuch  as  they  fail  to  describe  their  flours,  no  conclusions  can 
be  drawn  as  to  their  effect  on  flour  strength.  It  is  of  interest  to  note, 
however,  that  at  a  hydrogen  ion  concentration  of  about  pH  5,  (the  op- 
timum hydrogen  ion  concentration  in  the  making  of  bread  as  found 
by  Jessen-Hanson)  the  viscosity  of  dough,  made  from  four  different 
flours  is  at  a  minimum.  They  further  note  that  salts  such  as  sodium 
lactate,  NagSO^  MgSO^,  KBrO*  tend  to  decrease  the  viscosity  of  the 

8 


dough,  while  NaCl,  MgClg  NH^Cl  tend,  to  decrease  the  viscosity 
when  used  in  small  amounts,  but  on  further  addition  the  viscosity 
increases. 

Ostwald  (1919)  and  Liiers  (1919)  and  Liiers  and  Ostwald  (1919) 
(1920)  in  a- series  of  papers  show  the  remarkable  parallelism  existing 
between  viscosity  measurements  of  flour-water  mixtures  and  grade  of 
flour.  They  found  that  flours  divide  themselves  into  three  distinct 
groups  when  measured  in  this  way.  The  low  extraction  flours  (40%- 
607o)  constitutes  one  group,  the  high  extraction  flours  (60%-94%) 
a  second,  and  the  tailing  flours  (remains  of  60  %  -  94  %)  constitute 
the  third  group.  They  also  find  that  acids  and  bases  tend  to  in- 
crease the  viscosity  of  the  flour-water  mixtures  while  salts  tend 
to  depress  the  viscosity.  Their  results,  although  obtained  by  a  dif- 
ferent method,  confirm  the  work  of  Wood,  Wood  and  Hardy,  and  Up- 
son and  Calvin.  It  must  be  emphasized,  however,  that  their  results 
were  obtained  on  flours  of  diflferent  milling  extraction  and  the  dif- 
ferences they  obtained  refer  only  to  the  grade  or  degree  of  extraction 
of  the  flours,  and  do  not  necessarily  apply  directly  to  the  problem  of 
flour  strength. 

Sharp  and  Gortner  have  continued  the  work  of  Gortner  and  Do- 
herty,  and  confirm  the  findings  of  the  latter  in  regard  to  the  action  of 
acids  upon  gluten.  They  find  a  marked  diflference  in  the  rate  of  im- 
bibition when  using  the  various  alkali  hydroxides.  The  action  of  al- 
kalis on  gluten  is  markedly  different  from  that  of  acids,  as  dispersion 
takes  place  at  much  lower  concentrations.  They  remark  in  this  re- 
inspect,  "Indeed  dispersion  and  imbibition  are  here  almost  coincident." 
During  the  course  of  the  work  Sharp  and  Gortner  washed  out  the 
gluten  from  their  strong  and  weak  flours  and  dried  it  at  low  temper- 
ature in  vacuo.  After  pulverizing,  they  found  that  the  dried  glutens 
of  various  flours  were  much  more  alike  than  in  the  wet  state.  This 
observation  is  in  accord  with  their  theory  "that  the  strong  gluten  is 
strong  because  of  its  colloidal  properties ;  inasmuch  as  it  is  well  known 
that  the  alternate  wetting  and  drying  of  a  colloidal  gel,  breaks  down 
the  gel  structure."  They  also  find  that  the  optimum  hydrogen  ion  con- 
centration for  imbibition  is  the  same  for  the  dififerent  acids  used. 

In  their  next  paper  Sharp  and  Gortner  (1921)  extend  their  work  on 
the  hydration  capacity  of  glutens.  They  find  that  the  viscosimeter 
gives  an  accurate  measure  of  imbibition  in  that  the  curve  obtained  fol- 
lowed the  previous  curves  by  weighing  out  the  discs  of  gluten.  As 
might  be  expected,  they  found  that  the  strong  flours  give  much  greater 
viscosity  measurements  than  do  the  weak  flours. 
The  Carbohydrates  of  Wheat  Flour  and  Their  Relation     to     Flour 

Strength. 

The  carbohydrates  in  the  flour  have  also  been  investigated  with  ref- 

9 


erence  to  their  role  in  flour  strength.  Wood  was  perhaps  the  first  to 
make  any  definite  statement  in  this  respect,  although  Girard  and  Fleu- 
rent  (1903)  called  attention  to  the  great  variations  in  the  amounts  of 
*  sugars  in  the  flours.  They  found  on  analysis  that  glucose  and  cane 
sugar  were  present,  the  former  varying  from  0.09%  to  0.81%,  the  latter 
0.63%  to  1.89%.  Bruying  in  1906  considered  that  the  sugar  present  in 
flour  is  not  glucose  and  sucrose,  but  almost  entirely  maltose.  Liebig 
(1909)  supports  the  views  of  Girard  and  Fleurent  in  that  he  found 
wheat  flour  to  contain  from  1-1.5%  sucrose  and  0.1-0.4%  dextrose. 
Wood  thinks  that  strength  hinges  to  a  great  extent,  as  far  as  volume 
and  size  of  the  loaf  is  concerned,  upon  the  sugar  content  and  the  dias- 
tatic  enzymes  that  the  flour  contains.  He  sums  up  that  factor  in 
strength  dealing  with  volume  of  the  loaf  as  follows :  "The  factor  which 
primarily  determines  the  size  of  the  loaf  which  a  flour  can  make  is 
quite  distinct.  The  size  of  the  loaf  is  shown  to  depend  in  the  first 
instance  on  the  amount  of  sugar  contained  in  the  flour  together  with 
that  formed  in  the  dough  by  diastatic  action.  Particular  attention 
should  be  paid  to  the  rate  of  gas  evolution  in  the  later  stages  of  fer- 
mentation, as  this  is  shown  to  be  more  directly  connected  with  the  size 
of  the  loaf."  Wood's  method  of  measuring  the  gas-producing  capac- 
ity of  a  flour  consists  of  mixing  20  grams  of  flour  and  0.5  grams  of 
yeast  with  20  cc  of  water  in  stoppered  flasks  and  measuring  the  lib- 
erated carbon  dioxide  under  brine. 

Shutt  (1907)  shortly  after  Wood's  article,  determined  the  sugar  ex- 
tracted by  70  per  cent  alcohol  and  by  water  and  could  find  no  evidence 
"that  with  increase  of  sugar's  there  is  increase  of  volume  in  loaf,  but 
rather  the  reverse."     Shutt's  data  is  shown  in  Table  I. 

TABLE  I. 

Sugars  in  flour  extracted  by  70  per  cent  alcohql  and  water. 
(Data  taken  from  Shutt  [1907]   page  20). 

In  aqueous  extract  In  alcoholic  extract 

Directly  After  Directly  After 

Designation      reducing  Inversion  reducing  Inversion 

of                     as  as  Total  as  as  Total  Vol. 

Sample           Maltose  Sucrose  Sugars  Maltose  Sucrose  Sugars  Bakers 

%  %             %  %  %  %  Mark 

No.  1  Hard                1.96  2.14  4.10  .13  .91  1.04  492 

No.  1  Northern         2.73  1.95  4.68  .20  .94  1.14  443 

No.  2  Northern         1.87  1.79         3.66  .18  .87  1.05  438 

No.  3  Northern         3.42  2.10         5.22  .26  1.21  1.47  383 

No.  4  Com'cial  Gr.    3.62  2.43         6.05  .05  1.34  1.39  397 

No.  5  Com'cial  Gr.    3.63  2.43  6.06  .06  1.42  1.48  366 

No.  6  Com'cial  Gr.    4.07  2.43  6.50  .06  1.36  1.42  363 

Shortly  after  the  appearance  of  Wood's  paper,  Baker  and  Hulton 
(1908)  reported  a  paper  in  which  they  investigated  the  action  of  en- 


10 


zymes  contained  in  flour  with  regard  to  their  effect  on  flour  strength. 
Unable  to  demonstrate  experimentally  the  existence  of  proteolytic  en- 
zymes in  flour,  they  concluded  that  any  which  are  present  have  no  ef- 
fect upon  the  gluten  during  the  time  of  fermentation.  They  did 
show,  however,  that  the  proteolytic  enzymes  contained  in  yeast  play 
an  important  part,  since  one  dough  containing  yeast  showed  2.7%  sol- 
uble nitrogen  as  protein,  while  a  similar  dough  without  yeast  had 
1.9%  soluble  nitrogen  as  protein.  Although  the  fact  was  known  that 
wheat  flour  contained  amylolytic  enzymes,  Baker  and  Hulton  demon- 
strated their  presence  in  dough  by  an  increase  in  maltose,  extracting 
the  latter  with  water  and  preparing  the  maltosazone.  They  found 
that  contrary  to  expectations,  the  diastatic  activity  of  flours  increased 
with  age.  * 

Baker  and  Hulton  (1908)  show  that  the  total  volume  of  gas  pro- 
duced (same  method  as  outlined  by  Wood)  increases  roughly  with  in- 
crease in  baking  strength  (Baker's  Mark)  of  the  flour.  They  also 
point  out  that  a  weak  flour  may  have  a  diastatic  power  as  high  or  even 
higher  than  a  strong  flour.  This  is  explained  by  the  fact  that  in  real- 
ity the  weak  flour  is  deficient'  in  liquifying  enzymes  and  that  by  the 
addition  of  liquifying  enzymes  a  much  greater  volume  of  gas  is  given 
off,  while  a  strong  flour  shows  no  increase  in  gas  production  when  a 
diastatic  enzyme  is  added.  The  liquifying  enzymes  were  added  in  the 
form  of  a  malt  extract  and  Table  II  shows  that  even  such  smaller 
amounts  as  0.25  and  1.0  percent  caused  the  gas  production  to  increase 
enormously  in  a  weak  flour.  They  did  not  state  whether  the  addition 
of  the  malt  extract  did  actually  increase  the  baking  strength  of  the 
flour.  From  the  data  submitted.  Baker  and  Hulton  concluded  that 
weak  flours  in  some  instances  give  as  great  a  gas  production  as  do 
strong  flours,  and  that  gas  production  is  not  a  function  of  the  quan- 
tity of  diastases  but,  as  they  show,  (Table  III)  it  is  intimately  con- 
nected with  "the  additional  matter  rendered  soluble  during  the  process 
of  doughing,"  i.  e.  maltose. 

TABLE  II. 

Effects  of  added  malt  extract  upon  a  weak  flour  with  reference  to  an 

increase  in  gas  production.     (From  data  of  Baker 

and  Hulton  [1908]  page  372). 

0.25  Percent  1.0  Per  cent 

Time  Flour  Alone  of  Malt  of  Malt 

Hours  c.c.  CO2  c.c.  CO2  c.c.  CO2 

0.5                                28                                30                                32 
1.0                                47                                 66                                69 
1.5                                55                               101                               115 
14.0 113 245 362 

*(It  is  a  well-known  fact  that  flours  on  aging  show  greater  jjaking  strength 
and  this  increase  in  diastatic  activity  may  therefore  be  the  primary  cause  for 
increase  in  baking  strength  as  the  flour  ages.  At  any  rate  it  seems  to  be  in 
accord  with  Wood's  theory). 

11 


Differences 

Volume 

Maltose 

of  gas  ob- 

formed 

tained  from 

during 

dough  in 

Bakers 

doughing 

3  hours 

Mark 

1.48 

78 

45 

1.38 

84 

40 

2.53 

145 

76 

3.04 

155 

80 

3.88 

164 

95 

3.45 

175 

78 

6.75 

193 

90 

5.42 

217 

90 

4.S2 

220 

80 

5.02 

230 

91 

8.11 

270 

90 

TABLE  III. 

The  relation  between  gas  volume  and  the  additional  matter  rendered 

soluble  during  the  process  of  doughing.     (From  Baker  and  Hulton 

(1908)  page  372). 

Percent  of 
Matter  solubl 
Percent  of  in   dough 

matter    soluble      when  kept 
in  water  at       at  40°  C.  for 
Flour  15.5°C.  3  hours 

1  2.12  3.60 
X  2.03  4.41 
W                 2.83  5.38 

3  2.49  5.53 

Y  2.69  6.57 

2  3.19  6.66 

4  4.19  1095 

V  2.83  8.26 
T                  2.84  7.66 

•  U  2.65  7.68 

Z  3.54  11.65 

It  would  seem  from  the  above  table  that  low  strength  flours  are  de- 
ficient in  liquifying  enzymes  and  the  authors  conclude  that  the  liqui- 
fying enzymes  are  the  limiting  factors  in  the  production  of  maltose  in 
the  dough  stage. 

Simultaneously  with  the  appearance  of  Baker  and  Hulton's  article, 
the  work  of  Ford  and  Guthrie  (1908)  was  published  on  the  relation 
of  enzymes  contained  in  flour  to  its  baking  strength.  They  conducted 
experiments  of  extraction  and  found  that  amylases  could  be  greatly 
.stimulated  by  the  use  of  KCl  and  also  by  active  and  by  boiled  papain. 
In  testing  amylase  values  from  twelve  flours,  they  found  differences 
(using  KCl  and  papain  extracts)  varying  from  22. L  to  46.8  expressed 
in  grams  maltose  per  gram  of  dry  flour.  They  could  not  correlate 
diastase  activity  with  flour  strength  and  state  "It  however  indicates 
that  in  developing  a  method  of  evaluation,  the  total  amylase  is  one  im- 
portant factor,  also  that  the  presence  of  a  proteolytic  ferment  is  an- 
other and  possibly  more  valuable  consideration." 

Ford  and  Guthrie  (1908)  were  probably  the  first  to  demonstrate 
the  action  of  proteolytic  enzymes  in  flour.  They  were  unable  to 
secure  results  with  nitrogen  determinations  or  with  the  viscosi- 
meter,  so  they  tried  1  percent  gelatin.  The  liquification  of  the  gela- 
tin gave  them  positive  proof  of  proteolysis.  They  also  conducted 
baking  tests  with  a  large  amount  of  protease  added,  and  naturally 
the  loaf  did  not  rise  during  the  fermentation  period,  the  resultant 
bread  being  a  soggy  mass.  They  concluded  that  proteases  decrease 
gas  holding  properties  of  the  gluten  and  point  out  that  this  is  the 
chief  reason  for  failure  in  the  use  of  malt  extracts  in  baking  practise. 

Bailey  and   Weigley    (1922)    found   that   flour  strength   depended 

12 


upon  factors  which  control  the  rate  of  carbon  dioxide  production 
and  the  amount  of  carbon  dioxide  lost  during  fermentation.  They 
found  that  "the  loss  of  carbon  dioxide  per  unit  increase  in  volume 
under  controlled  conditions  afifords  a  useful  measure  of  gas-holding 
capacity  of  dough." 

In  some  unpublished  data  Thatcher  and  Kennedy  show  that 
when  flour  was  digested  with  w^ater,  the  amounts  of  reducing  sugars 
in  the  extract  increased  regularly  with  increase  in  temperature.  A 
centrifuged  aliquot  of  a  flour  water  extract  likewise  increases  in 
soluble  nitrogen  with  increase  in  temperature  of  extraction.  They 
also  found  that  no  increase  in  reducing  sugars  takes  place  when  a 
filtered  extract  (0°-5°C)  of  flour  is  allowed  to  act  on  soluble  starch 
when  incubated  at  40°,  50°  and  60° C.  Under  these  conditions  they 
assume  that  absorption  of  the  enzyme  or  activator  has  taken  place 
upon  the  filter  paper  or  upon  the  gluten  colloids. 

Historical  Review  of  the  Study  of  Diastatic  Enzymes. 

In  taking  up  the  history  of  the  diastases,  one  is  confronted  with 
a  voluminous  and  at  times  conflicting  literature,  which  extends  back 
over  a  period  of  one  hundred  years  or  more.  Naturally,  a  great 
deal  has  to  be  discarded,  as  it  would  be  impossible  to  review  any  but 
the  most  important  papers  submitted  on  this  question.  Neverthe- 
less it  is  my  intention  to  cite  a  number  of  papers  which  are  of  in- 
terest from  a  purely  historical  viewpoint. 

Vauquelin  in  1811  was  the  first  to  record  the  fact  that  when 
starch  was  heated  in  water,  it  gave  an  opaque  solution  and  had  the 
characteristics  of  gum  arabic.  In  the  same  year  Kirchoff  found 
that  when  starch  was  boiled  with  dilute  HgSO^,  a  crystallized 
sugar  was  formed.  Two  years  later  he  noted  that  the  protein  of 
the  embryo  of  the  seed,  particularly  if  the  seed  had  been  germinated, 
acted  on  starch  in  much  the  same  manner  as  did  the  acid.  He  real- 
ly was  the  first  to  record  diastatic  activity  but  did  not  realize  the 
importance  of  his  observations.  Vogel  in  1812  found  that  when 
starch  was  boiled  with  acid,  it  gave  two  products,  a  sugar  and  a 
gummy  substance,  the  latter  now  known  as  dextrin.  Stromeyer 
in  1813  found  that  iodine  was  a  specific  reagent  for  starch  and  visa 
versa,  while  tbe  action  of  alkaline  copper  sulphate  was  found  by 
Trommer  in  1841  to  be  a  means  of  distinguishing  sugar  from  starches 
and  gums. 

The  gummy  substance  found  by  Vogel  was  investigated  by  Biot 
and  Persoz  in  1853  and  was  found  to  turn  the  plane  of  polarized 
light  to  the  right.  For  this  reason  it  was  given  the  name  of  dex- 
trin. It  is  of  interest  to  note  that  the  work  of  Biot  and  Persoz 
formed  the  basis  for  the  development  of  our  present  day  polaris- 

13 


cope.  In  the  same  year  Payen  and  Persoz  conclusively  established 
the  fact  that  an  extract  of  malted  grain  had  a  powerful  action  in 
liquifying  and  saccharifying  starch.  They  ascribed  this  function 
to  some  inner  substance  and  named  it  diastase.  It  had  been  the 
impression  of  chemists  up  until  this  time  that  glucose  was  the  sugar 
formed  when  starch  was  acted  upon  by  diastase  and  it  was  not  until 
1872-1876  that  O'Sullivan  showed  it  to  be  maltose.  O'Sullivan 
found  the  optical  rotation  to  be  too  high  and  the  reducing  power 
too  small  to  correspond  with  glucose.  It  might  be  of  interest  to 
call  attention  to  the  discovery  of  maltose  at  this  time.  Although 
DeSassure  had  accurately  described  maltose  in  1819  the  fact  had 
evidently  been  forgotten  until  Dubrunfaut  called  attention  to  it  in 
1847  and  named  it  maltose.  This  rediscovery  was  again  forgotten 
until  it  was  again  described  by  O'Sullivan  in  1872. 

Marker  in  1877  states  that  at  a  temperature  of  60° C  four  mole- 
cules of  starch  yield  three  of  maltose  and  one  of  dextrin,  under 
the  influence  of  diastatic  ferments.  At  65°  the  yield  of  maltose  is 
lowered  and  at  still  higher  temperatures  two  molecules  of  starch 
yield  one  of  dextrin  and  one  of  maltose.  Marker  concludes  that 
there  are  two  diastatic  ferments,  one  producing  dextrin  and  the  oth- 
er maltose.  This  is  our  present  day  conception  of  the  diastases,  one 
being  termed  the  liquifying  and  the  other  the  saccharifying  enzyme. 
Musculus  and  Gruber  in  1878  regarded  starch  as  a  polysaccharide, 
containing  five  or  six  times  the  group  C12H20O10.  Under  the  action 
of  diastase  or  acids,  the  carbohydrate  undergoes  a  series  of  changes 
of  hydration  and  successive  decomposition,  resulting  in  maltose  and 
dextrin  of  less  molecular  weight.  Brown  and  Heron  in  1879  found 
that  the  heating  of  a  diastatic  solution  diminishes  its  activity  and 
that  an  increase  in  temperature  increases  its  activity  up  to  66°,  beyond 
which  not  much  activity  is  shown.  They  also  found  that  alkalies 
markedly  reduce  the  activity  of  a  malt  extract. 

It  was  in  1879  that  Kjeldahl  stated  his  law  of  proportionality 
in  regard  to  the  action  of  diastases.  He  determined  the  reducing 
power  of  malt  extract  and  saliva  on  an  excess  of  starch  at  57°-59°. 
He  conisdered  that  the  reduced  copper  was  directly  proportional  to 
the  amount  of  amylase  present  and  was  a  true  measure  of  diastatic 
power  so  long  as  digestion  was  not  carried  above  40  per  cent  of  the 
starch  present.  Grief smayer  a  year  later,  confirmed  Kjeldahl's  work 
and  the  law  of  proportionality. 

Up  to  about  this  time  the  polariscope  and  the  cupric  reducing 
method  had  been  used  to  estimate  the  diastatic  power  of  malt  ex- 
tract by  the  amount  of  maltose  formed.  The  iodine  reaction  was 
made  use  of  by  Roberts  in  1881,  however,  and  he  defined  the  dias- 

14 


tatic  power  of  pancreatic  extracts,  saliva,  and  malt  extracts,  as  the 
number  of  cubic  centimeters  of  a  standard  starch  paste  which  could 
be  converted  by  one  cubic  centimeter  of  the  active  solution  during 
five  minutes  at  40°  into  products  giving  no  color  reaction  with 
iodine. 

Jungk  two  years  later  published  a  method  of  determining  the 
diastatic  activity  of  a  malt  extract  by  the  iodine  method  which  was 
similar  to  the  method  of  Roberts.  He  determined  the  time  re- 
quired for  10  cc  of  extract  to  convert  10  grams  of  starch  which  he 
considered  should  not  exceed  10  minutes,  for  a  good  malt.  His 
temperature  of  digestion  was  40°. 

From  the  literature  already  cited,  two  methods  of  determining 
the  diastatic  activity  of  an  amylase  preparation  had  come  into  use, 
namely  the  iodine  or  the  so-called  liquifaction  method,  which  mea- 
sures the  power  of  the  amylase  to  completely  convert  the  starch  into 
products  which  no  longer  give  the  characteristic  color  with  iodine, 
and  the  reduction  or  saccharification  method  in  which  the  amounts 
of  reducing  sugars  are  estimated  by  means  of  alkaline  copper 
sulphate.  The  development  of  the  iodine  method  from  the  time  of 
Jungk  will  be  the  first  considered. 

Iodine  Method  for  the  Estimation  of  Diastatic  Activity. 

Francis  in  1898  made  the  next  improvement  in  the  iodine  method 
by  laying  down  very  exact  rules  for  the  determination  of  the  end 
point  in  the  iodine  starch  reaction.  He  also  extended  the  time  of 
digestion  from  10  minutes  to  half  an  hour.  Takamine  in  the  same 
year  developed  a  different  procedure.  He  first  standardized  a  sample 
of  taka-diastase,  which  was  found  to  keep. its  diastatic  power  for  a 
considerable  length  of  time.  He  then  determined  the  relative  amounts 
of  standard  and  sample  to  be  tested,  which  are  required  to  accomplish 
the  same  amount  of  conversion  in  the  same  length  of  time.  In  these 
determinations  he  used  iodine  to  test  for  the  end  point. 

The  next  important  work  was  carried  out  by  Wohlgemuth  in  1908. 
He  established  a  new  standard  which  was  based  on  the  number 
of  cubic  centimeters  of  1  percent  starch  solution  which  1  cc  of  dias- 
tatic ferment  could  convert  in  30  minutes  at  40°C.  The  method 
consists  of  measuring  out  5  cc  of  a  1  percent  starch  solution  into 
each  of  a  series  of  test  tubes  and  then  adding  different  amounts  of 
a  diastatic  solution  to  each.  At  the  end  of  a  half  hour  at  40°  the  test 
tubes  are  transferred  to  an  ice  bath.  After  cooling  each  tube  was 
shaken  up  with  a  definite  amount  of  iodine  solution  and  the  one 
which  showed  no  trace  of  color  was  taken  for  the  end  point. 

Johnson  in  1908  improved  the  technique  of  Francis,  and  Jungk,  by 

15 


preparing  a  starch  paste  (potato)  of  constant  value.  He  added  his 
diastatic  preparations  to  a  fixed  amount  of  starch  and  withdrew 
portions  and  tested  with  iodine,  at  the  end  of  ten  minutes.  When 
close  to  the  end  point,  he  tested  more  frequently,  repeating  with 
smaller  increments  of  sample,  until  the  amount  was  found  which 
would  in  ten  minutes  just  convert  the  starch. 

Sherman  and  Schlesinger  (1913)  and  Sherman  and  Thomas  (1915), 
used  the  method  of  Wohlgemuth  in  determining  amyloclastic  activity. 
They  stipulate  a  definite  color  for  the  end  point  of  the  iodine  reaction, 
using  the  Milton  Bradley  color  chart  as  given  by  Mullikin  in  his 
"Identification  of  Pure  Organic  Compounds." 

If  the  iodine  method  is  to  be  used  it  appears  probable  that  the  most 
accurate  results  can  be  obtained  by  following  the  technic  described 
by  Sherman  and  his  various  co-workers. 

Copper  Reduction  Method  for  the  Determination  of  Reducing  Sugars 
Formed  by  the  Action  of  Diastase. 

Although  Kjeldahl  showed  that  the  reducing  sugars  formed  by 
the  action  of  diastatic  enzymes  upon  an  excess  of  starch  was  a 
measure  of  their  activity,  no  great  advance  was  made  in  the  exact 
valuation  of  diastase  preparations  until  1886,  when  Lintner  modified 
Kjeldahl's  method.  He  first  prepared  a  soluble  starch  possessing 
rather  definite  characteristics.  He  was  then  enabled  to  base  his  calcu- 
lations of  diastatic  power  upon  the  production  of  a  constant  quantity 
of  maltose  formed  by  the  action  of  the  malt  extract  upon  a  definite 
amount  of  soluble  starch.  His  method  consisted  of  measuring  10  cc. 
of  a  2  per  cent  soluble  starch  solution  into  a  series  of  ten  test  tubes, 
to  each  tube  he  added  a  slightly  diflferent  amount  of  malt  extract. 
After  digesting  exactly  one  hour  at  21  °C.,  5  cc.  of  Fehling  solution 
is  added  to  each  tube  and  the  whole  series  of  tubes  are  placed  in 
boiling  water  for  ten  minutes,  and  then  examined  to  determine  the 
first  tube  in  which  all  the  copper  was  reduced.  Lintner  prepared  a 
diastase,  of  which  .12  mg.  was  able  to  produce  the  required  amount 
of  maltose,  under  the  above  conditions,  to  completely  reduce  5  cc.  of 
Fehling's  solution.  To  this  preparation  Lintner  gave  the  value  of 
100  and  the  power  of  the  samples  were  calculated  as  inversely  pro- 
portional to  the^  amount  of  sample  required  to  produce  this  fixed 
amount  of  reducing  sugar. 

Ford  (1904)  prepared  a  soluble  starch  from  various  sources  and 
after  careful  purification,  similar  to  the  Lintner  method,  concluded 
that  no  diflference  was  attributable  to  the  source  of  the  starch.  He 
specified  that  soluble  starch  should  be  neutral  to  rosolic  acid  in  order 
to  give  concordant  results  by  the  Lintner  method. 

16 


Ford  and  Guthrie  (1908)  expressed  amylolytic  activity  as  grams  of 
maltose  produced  by  a  filtered  extract  of  one  gram  of  mashed  barley 
in  an  excess  of  soluble  starch  for  one  hour  at  40°C. 

Several  other  copper  reduction  methods  have  found  their  way  into 
use  since  Lintner  established  his  method  for  determining  diastatic 
activity  by  measuring  the  reducing  sugars  formed.  The  most  notable 
is  that  of  Sherman,  Kendall  and  Clark  (1910).  This  method  consists 
of  placing  different  amounts  of  enzyme  e.  g.,  0.2,  0.5,  0.8,  and  1.0 
mgms.  into  four  erlenmeyer  flasks,  to  this  is  added  100  cc.  of  a  2  per 
cent  soluble  starch  and  the  whole  digested  30  minutes  at  40°C.  At 
the  end  of  this  time,  50  cc.  of  Fehling  solution  are  added  and  the  flasks 
are  immersed  in  a  boiling  water  bath  for  15  minutes.  The  reduced 
CU2O  is  then  quickly  filtered  and  determined  gravimetrically.  They 
supply  a  table  which  gives  diastatic  activity  of  the  preparation  called 
the  "new  scale." 

Influence  of  Temperature  on  Diastatic  Activity. 

In  all  of  the  earlier  work  high  temperatures  were  employed,  that 
is  between  40°-60°C.  Marker  found  that  at  60°  four  molecules  of 
starch  formed  three  of  maltose  and  one  of  dextrin,  while  at  65°  the  yield 
was  lowered  and  only  one  molecule  of  maltose  and  one  of  dextrin  were 
formed  from  two  of  starch.  It  is  quite  obvious  from  our  present  day 
knowledge  that  the  optimum  temperature  for  diastatic  activity  lies 
between  63°-65°C.,  which  would  explain  why  Marker  got  a  decreased 
production  of  maltose  at  65  °C. 

Brown  and  Heron  (1879)  found  that  previous  heating  of  a  malt 
extract  decreased  its  activity  to  a  great  extent.  They  found  that  it 
showed  very  litle  activity  when  heated  above  66° C. 

Vernon  (1901-1902)  gives  the  optimum  temperature  for  the  activity 
of  diastase  as  35°'C.  with  continued  activity  up  to  65°C. 

Kendall  and  Sherman  (1910)  find  the  optimum  temperature  of  puri- 
fied amylases  to  be  40°  in  the  presence  of  salts  and  a  trace  of  alkali. 
They  find  that  between  20°-40°  the  activity  is  about  doubled  for  each 
10°  increase  in  temperature  with  a  considerable  falling  off  in  rate  of 
increase  of  activity  betwen  40°-50°,  where  the  maximum  activity 
was  found. 

Influence  of  Acids,  Bases  and  Salts  on  Diastatic  Activity. 

The  effects  of  acids  and  bases  upon  diastatic  activity  has  received 
a  great  deal  of  attention,  some  investigators  claiming  that  an  acid 
medium  was  the  most  favorable,  while  others  advocate  a  neutral 
medium,  for  the  optimum  activity  of  the  enzyme. 

Baswitz  (1878-1879)  and  Mohr  (1903)  found  that  when  carbon 
dioxide  was  passed  through  the  reacting  medium,  a  great  increase  in 

17 


diastatic  activity  took  place.  Detmer  (1882)  reached  the  same  con- 
clusion and  noted  that  small  amounts  of  citric,  phosphoric  and  hydro- 
chloric acids  had  an  activating  effect.  Reychler  (1889)  found  that 
KH2PO4  had  a  stimulating  effect,  while  Effront  noted  that  HCl, 
HF,  H2SO4  and  phosphoric  acid  as  well  as  KHoPO^  had  a  very 
favorable  action.  Petit  (1904)  found  an  acid  medium  to  be  the  best. 
Kjeldahl  (1880)  reported  that  H2SO4  when  in  a  concentration  of 
.005  N.  increased  diastatic  activity,  but  was  decidedly  detrimental 
when  .01  N.  was  used.  The  same  concentrations  hold  for  citric  and 
acetic  acids  as  reported  by  Schneidewind,  Meyer  and  Miinter  (1906). 

Heyl  finds  that  KHgPO^  has  an  activating  as  well  as  a  conserving 
action,  while  Hawkins  (1913)  reports  that  small  additions  of  phos- 
phoric, acetic  and  tartaric  acids  increase  the  saccharogenic  power  of 
the  malt  extract  but  did  not  effect  the  amyloclastic  activity. 

Chittenden  and  Cummins  (1884),  Duggan  (1885),  Lintner  (1885), 
Ford  (1904),  Maquenne  and  Roux  (1906)  and  Fernbach  and  Wolff 
(1907)  are  all  agreed  that  a  neutral  medium  is  the  most  favorable  for 
diastatic  activity. 

Sherman  and  Thomas  (1915)  and  Sherman,  Thomas  and  Baldwin 
(1919)  find  that  the  optimum  diastatic  activity  for  various  diastatic 
preparations,  depending  upon  their  source,  is  at  a  pH  of  4.2-4.6.  They 
report  an  optimum  hydrogen  ion  concentration  of  about  pH  4.4  for  a 
diastase  prepared  from  malt  extract,  a  pH  of  about  4.7  for  the  amylase 
of  Aspergillus  oryzae  and  a  pH  of  6.8-7.0  for  pancreatic  amylase. 
After  reaching  the  optimum  pH  the  activity  falls  off  very  sharply  on 
the  alkaline  side. 

Many  substances  have  likewise  been  reported  which  activate  dia- 
static preparations  such  as  asparagine,  aspartic  acid,  different  amino 
acids  and  proteins.  Chief  among  the  workers  who  have  reported 
such  results  are  Effront  (1904),  Ford  (1904),  Rockwood  (1917),  Sher- 
man and  Walker  (1921)  and  Sherman  and  Caldwell  (1921). 

Very  little  work  is  reported  on  the  action  of  alkalis  upon  diastatic 
activity.  Brown  and  Heron  report  a  decided  falling  off  in  diastatic 
activity  when  Ba(OH)2,  KOH  or  NaOH  is  added  to  the  medium. 
In  fact,  it  has  been  the  custom  to  use  Alkalies  to  stop  diastatic  activity 
in  solutions  being  analyzed. 

Effects  of  Proteolytic  Enzymes. 
The  action  of  proteolytic  enzymes  upon  protein  material  is  well 
understood  today  and  needs  very  little  mention.  In  regard  to  the 
action  of  proteolytic  enzymes  in  flour.  Ford  and  Guthrie  were  not 
able  to  show  by  any  chemical  means  that  they  existed  in  wheat  flour. 
However,  when  1  per  cent  gelatin  was  added  to  the  flour  and  then 

18 


allowed   to   solidify,   proteolysis    could   be   followed   by   the   gradual 
liquification  of  the  gelatin. 

Baker  and  Hulton  could  find  no  method  to  establish  the  presence 
of  proteolytic  enzymes  in  flour  and  therefore  claim  that  any  which 
may  be  present  would  have  very  little  effect  upon  a  dough.  They  did 
demonstrate,  however,  that  yeast  contains  a  very  powerful  protein 
splitting  enzyme,  as  shown  by  the  soluble  nitrogen  of  two  identical 
doughs,  one  with  and  the  other  without  yeast.  In  the  dough  to 
which  yeast  had  been  added,  they  report  2.7  per  cent  soluble  nitrogen 
as  protein,  while  in  the  other  dough  they  found  only  1.9  per  cent 
soluble  nitrogen  as  protein. 

Hydrogen  Ion  Concentration. 

From  the  foregoing  literature,  it  has  been  shown  that  acids,  bases 
and  salts  are  of  the  utmost  importance  in  relation  to  the  activity  of 
diastatic  ferments.  Jessen  Hanson  has  also  shown  that  the  optimum 
conditions  for  the  baking  of  bread  occur  when  the  dough  is  at  a 
hydrogen  ion  concentration  of  about  pH  5.0. 

Bailey  and  Peterson  (1921)  find  that  when  acid  or  alkali  is  added 
to  buffered  water  extracts  of  flour,  a  characteristic  curve  is  obtained 
which  indicates  very  accurately  the  grade  and  baking  qualities  of  a 
flour.  Bailey  and  Collatz  (1921)  have  shown  that  a  remarkable 
parallelism  exists  between  grade  of  flour  and  the  electrical  conduc- 
tivity of  a  water  extract  of  flour  when  digested  one  hour  at  25 °C. 

Viscosity. 

Although  Ford  and  Guthrie  attempted  to  demonstrate  the  proteo- 
lytic action  of  enzymes  in  wheat  flour,  by  digesting  the  flour  in  water 
at  a  set  temperature  by  means  of  viscosity  measurements,  they  report 
no  success  in  this  method. 

Ostwald  and  Liiers  in  a  series  of  papers  show  that  different  mill 
grades  of  flours  can  be  distinguished  by  means  of  a  viscosimeter. 
From  their  data,  the  flours  group  themselves  according  to  the  degree 
of  extraction  in  milling. 

Quite  recently  Sharp  and  Gortner  have  demonstrated  the  efficiency 
of  the  viscosimeter  in  measuring  differences  in  the  imbibitional  capac- 
ity of  strong  and  weak  flours  when  treated  with  various  acids,  bases 
and  salts.  They  find  that  strong  flours  show  a  greater  viscosity  under 
the  conditions  of  their  experiments  than  do  the  weak  flours. 

From  the  literature  cited  one  may  judge  the  amount  of  work 
expended  upon  the  question  of  flour  strength.  Although  the  work 
of  the  last  few  years  shows  progress  on  this  question,  we  do  not  have 
a  single  test  which  gives  us  an  absolute  criterion  of  flour  strength 

19 


and  it  is  still  necessary  to  fall  back  upon  the  baking  tests  to  have 
a  final  answer  to  the  question. 

II.  EXPERIMENTAL, 
(a)  The  Problem. 

It  has  been  shown  in  the  historical  review  that  flour  strength  has 
been  studied  in  a  variety  of  ways.  Two  points  of  attack  are  outstand- 
ing, however,  the  work  of  Wood  and  Hardy,  Upson  and  Calvin, 
Gortner  and  Doherty,  and  Sharp  and  Gortner,  who  have  concerned 
themselves  with  the  physico-chemical  properties  of  the  gluten ;  and 
of  Baker  and  Hulton,  and  Ford  and  Guthrie  who  have  attacked  the 
problem  from  the  enzymic  standpoint.  In  this  Thesis  we  are  con- 
cerned with  enzyme  relationships.  From  the  data  presented  by  Ford 
and  Guthrie  it  would  appear  that  the  diastatic  enzymes  were  of  more 
importance  than  the  proteolytic  enzymes  with  regard  to  flour  strength. 

Baker  and  Hulton  indicate  in  their  excellent  work  that  the  amy- 
loclastic  enzymes  were  perhaps  the  limiting  factor  in  the  production 
of  maltose.  I  have  taken  up  the  problem  at  this  point  and  am  con- 
cerned with  the  effect  upon  the  baking  strength  of  wheaten  flours 
when  diastatic  ferments  are  added  to  the  dough.  As  the  diastatic 
preparations  available  for  the  baker  are  in  the  form  of  malt  flours 
and  malt  extracts  which  contain  proteolytic  enzymes,  the  problem 
is  at  once  broadened  to  include  the  later  as  well  as  the  starch  splitting 
ferments. 

(b)  Material. 

The  present  investigation  was  conducted  with  a  commercial  malt 
•flour,  a  representative  malt  extract,  a  commercial  sample  of  wheat 
starch,  and  a  series  of  seven  wheat  flours  of  different  grades  milled 
from  wheats  grown  in  different  regions  of  North  America.  All  of 
the  flour  samples  and  malt  preparations  were  submitted  to  careful 
chemical  analysis  and  in  most  cases  were  rechecked  by  other  inves- 
tigators using  the  same  materials.  The  buffer  values  of  the  flour 
extracts  were  also  determined  by  the  method  of  Bailey  and  Peterson 
in  order  to  have  additional  data  as  to  the  grade  of  the  flour.  This 
data  is  given  in  Table  VII. 

Description  of  Materials  Used  in  These  Studies. 

The  flours  used  in  this  investigation  were  flours  milled  from  auth- 
entic samples  of  wheat,  grown  in  different  regions  of  North  America 
under  different  climatic  conditions.  The  A.  O.  A.  C.  methods  were 
followed  in  analyzing  the  flours  and  malt  preparations,  with  the 
results  shown  in  Tables  IV,  V,  and  VI.  A  description  of  the  wheat 
flours  is  as  follows : 

20 


Flour  1001  was  milled  from  a  sample  of  hard  Kansas  wheat  from 
the  crop  of  1921.  The  baking  tests  showed  it  to  be  of  good  strength 
and  the  low  ash  content.  Hydrogen  ion  concentration,  in  terms  of 
pH,  show  it  to  be  a  patent  of  low  extraction.  The  protein  content, 
which  is  a  trifle  low,  reflects  directly  upon  its  baking  strength. 

TABLE  IV. 
Analysis  of  Wheat  Flours  on  Air  Dry  Basis. 


ir  Samples 

Protein 

)oratory 

Moisture 

Ash 

(Nx5.7) 

Milling 

pH  of  Water 

No. 

Percent 

Percent 

Percent 

Grade 

Extract 

1001 

12.15 

.40 

11.34 

Patent 

5.816 

1002 

12.14 

.61 

13.00 

Clear 

6.052 

1003 

13.06 

.46 

8.83 

Patent 

6.002 

1007 

11.06 

.64 

14.12 

Clear 

6.103 

1008 

11.70 

.46 

15.32 

Patent 

6.133 

1009 

11.61 

.42 

13.81 

Patent 

5.981 

1011 

11.44 

.56 

10.77 

Patent 

6.050 

TABLE  V. 
Analysis  of  Malt  Flour  on. Air  Dry  Basis. 


Malt  Flour 

Laboratory  Moisture     Ash      Protein 
No.  Percent  Percent  Percent 


Total 

Reducing 

Sugars 

Sugars 

as  Dex-     Diastatic  Value 

as  Dextrose 

trose              Degrees 

Percent 

Percent            Lintner 

24 


8.8 


1.26 


11.25 


4.75 


10.62 


177.05 


TABLE  VI. 
Analysis  of  Malt  Extract. 

Reducing  Sugars  Total  Sugars                 Dias- 

Calculated  Calculated  as  Pro-      tatic 

Ex-                     Ash                       Dex-  Dex-  tein     Value 

tract    Moisture  Per-   Maltose      trose  Maltose      trose  Per-  Degrees  Specific 

No.      Percent    cent    Percent   Percent  Percent   Percent  cent  Lintner  Gravity 

D         25.63       1.35       73.74        42.52  73.80        42.62  6.06      37.1          1.384 

Flour  1002  was  milled  from  a  sample  of  hard  Kansas  wheat.  The 
high  ash  content  and  the  pH  of  the  water  extract  indicate  a  clear 
flour.     The  baking  tests  show  it  to  have  a  fair  degree  of  strength. 

Flour  1003  is  a  patent  milled  from  soft,  white  winter,  Washington 
wheat.  The  ash  content  and  the  pH  of  the  water  extract  indicate 
a  patent  flour,  while  the  protein  content  and  the  baking  tests  show 
it  to  be  an  exceptionally  weak  flour. 

Flour  1007  is  a  clear  flour  milled  from  a  sample  of  selected  hard 
spring  wheat  grown  near  Calgary,  Canada.  The  ash  content  and  the 
pH,  of  the  water  extract,  show  it  to  be  a  clear  flour.  Although  the 
protein  content  is  high  the  baking  tests  show  it  to  be  of  poor  baking 
strength. 

Flour  1008  is  a  patent  milled  from  selected  hard  spring  Canadian 


21 


wheat,  and  shows  up  exceptionally  strong  in  the  baking  tests.  This 
flour,  it  would  seem,  is  too  strong  for  any  ordinary  baking  purposes 
and  would  have  to  be  blended  with  a  weaker  flour. 

Flour  1009  is  a  composite,  commercial  patent  flour,  milled  from 
hard  spring  wheat  for  a  select  trade.  The  ash  content  and  pH  values 
show  it  to  be  a  low  extraction  patent,  while  the  baking  tests  show 
it  to  be  a  very  strong  flour.  Flour  1009  does  not  give  the  volume  of 
loaf  that  flour  1008  does,  but  it  produces  bread  with  a  better  grain 
and  texture.  This  flour  is  the  only  one  of  the  series  in  which  the 
origin  of  the  wheat  is  not  known. 

Flour  1011  is  a  patent  flour  milled  from  Ohio  winter  wheat.  The 
baking  tests  show  it  to  be  of  rather  poor  baking  strength. 

TABLE  VII. 

Hydrogen  Ion  Concentration  after  addition  of  Acid  and  Alkali 
to  Flour  Extracts  as  an  Index  of  Buffer  Value. 


Malt 

Flour  No. 

1001 

1002 

10O3 

1007 

1008 

1009 

1011 

Flour 

cc.  N/50 

HCl 
Added 

pH 

pH 

pH 

pH 

pH 

pH 

pH 

pH 

12.5 

2.519 

2.958 

2.654 

2.894 

2.514 

2.510 

2.789 

3.904 

10.0 

2.654 

3.006 

2.874 

3.359 

2.876 

2.705 

2.977 

4.225 

7.5 

2.925 

3.320 

3.144 

3.799 

3.192 

2.992 

3.210 

4.428 

5.0 

3.388 

3.685 

3.761 

4.471 

3.545 

3.496 

3.630 

4.727 

2.5 

4.150 

4.666 

4.623 

5.158 

4.502 

4.272 

4.426 

5.166 

0.0 

5.816 

6.052 

6.002 

6.103 

6.153 

5.981 

6.050 

5.491 

(cc.N/50 

NaOH) 

2.5 

7.371 

6.931 

7.726 

6.938 

7.499 

7.792 

7.048 

6.071 

5.0 

9.045 

8.021 

9.653 

7.852 

8.906 

8.892 

8.883 

6.390 

7.5 

9.755 

9.146 

10.557 

8.926 

9.609 

9.91S 

9.540 

6.652 

10.0 

10.253 

9.772 

10.877 

9.535 

9.919 

10.448 

10.177 

6.888 

12.5 

10.617 

10.202 

11.022 

10.062 

10.249 

10.769 

10.464 

7.136 

(c)  The  Methods. 

The  Munson  and  Walker  method  for  the  determination  of  reducing 
sugars  was  used  throughout  the  investigation  for  the  estimation  of 
sugar  resulting  from  diastatic  activity,  and  all  the  results  are  calcu- 
lated as  dextrose.  In  the  cases  where  proteolytic  activity  is  deter- 
mined, the  amino  nitrogen  method  of  Van  Slyke,  and  the  viscosity 
method  of  Sharp  and  Gortner  were  used. 

The  Method  of  Determining  Diastatic  Activity. 

It  was  evident  from  the  very  first  that  the  method  of  Lintner,  for 
the  determination  of  diastatic  activity  was  out  of  the  question,  as 
were  also  the  other  methods  which  have  since  been  developed.  It 
was  also  evident  that  the  raw  starch  of  the  flours  was  the  natural 

22 


substrate  of  the  enzymes  and  consequently  should  be  used  to  dupli- 
cate, as  far  as  possible,  the  changes  taking  place  in  the  fermentation 
process.  Many  difficulties  were  involved  and  clarification  of  the  solu- 
tion was  necessary  to  obtain  uniform  results.  The  method  finally 
adopted  was  one  which  was  developed  and  perfected  in  this  laboratory. 
It  consisted  of  adding  3  cc.  of  15%  NagWO^  to  the  digestion  mixture, 
transferring  to  a  200  cc.  volumetric  flask  and  then  adding  20  drops  of 
concentrated  HgSO^  and  filling  up  to  the  mark  with  water.  After 
careful  and  thorough  shaking  the  contents  were  transferred  to  centri- 
fuge tubes  and  whirled  5  minutes.  The  resulting  clear  supernatant 
liquid  contained  all  the  soluble  sugars  and  was  practically  free  of 
soluble  protein  as  demonstrated  by  repeated  Kjeldahl  determinations. 
For  further  data,  see  report  on  diastatic  enzymes  of  wheat  flour  and 
their  relation  to  flour  strength.    (Rumsey,  1922). 

In  determining  the  diastatic  activity  of  a  malt  preparation  and  the 
amount  of  soluble  sugars  produced  from  the  flours  by  its  action,  the 
following  method  was  used:  Ten  grams  of  flour  were  weighed  out 
and  transferred  to  a  400  cc.  erlenmeyer  flask,  the  specified  amount 
of  flour  or  malt  extract  was  then  added.  One  hundred  cc.  of  water, 
previously  brought  to  temperature,  was  then  added  and  the  whole 
was  thoroughly  mixed  and  placed  in  a  water  bath,  for  1  hour  at  27°  C. 
The  flasks  were  agitated  every  five  minutes  and  at  the  end  of  the 
digestion  period  the  contents  of  the  digestion  flasks  were  transferred 
to  a  200  cc.  volumetric  flask  (any  starch  particles  adhering  to  the 
sides  of  the  flask  can  be  removed  with  a  rubber  policeman  and  a 
stream  of  water  from  the  wash  bottle)  and  clarified  as  described 
above.  After  clarification  50  cc.  aliquots  were  transferred  to  400  cc. 
beakers  and  the  reducing  sugars  determined  by  th»  Munson  and 
Walker  method. 

In  determining  the  reducing  sugars  formed  in  the  dough  at  various 
stages  of  fermentation  essentially  the  same  methods  were  followed. 
At  the  time  specified,  ten  grams  of  dough  are  pinched  off  from  the 
fermenting  mass  and  rubbed  up  in  a  mortar  with  a  little  water  until 
a  homogeneous  suspension  is  secured,  this  is  then  transferred  to  a 
250  cc.  volumetric  flask  and  the  same  procedure  followed  as  outlined 
above. 

The  Method  of  Determination  of  Proteolytic  Activity. 

In  the  determination  of  proteolytic  activity  eighteen  grams  of  flour 
(calculated  on  the  dry  basis)  were  weighed  and  transferred  to  a  500 
cc.  erlenmeyer  flask,  malt  flour  or  malt  extract  was  added  and  100  cc. 
of  water,  previously  brought  to  temperature  of  digestion,  was  then 
added  and  the  whole  digested  4  hours  at  40° C.     The  mixture  was 

23 


then  cooled  to  25°C,  at  the  close  of  digestion,  and  poured  into  the 
cup  of  the  MacMichael  viscosimeter  and  the  average  of  three  readings 
taken.  Then  5  cc.  of  N/1  lactic  acid  was  added,  the  contents  thor- 
oughly mixed,  and  the  average  of  three  successive  readings  taken. 
From  the  calibrated  scale  reading  of  the  MacMichael  Viscosimeter, 
w^hich  is  denoted  as  M,  any  values  such  as  centipoise  or  absolute 
viscosity  can  be  determined  by  calculation. 

Method  of  Determining  Buffer  Value  of  Flours. 

In  the  determination  of  the  buffer  values  of  the  flours,  80  grams 
of  flour  are  w^eighed  into  a  2  liter  flask  and  400  cc  of  water  added. 
The  whole  is  well  shaken  up  to  get  rid  of  any  lumps  and  digested 
1  hour  at  25  °C.  The  digestion  mixture  is  then  centrifuged  to  throw 
down  the  suspended  matter.  Aliquot  portions  of  25  cc.  volume  were 
treated  with  2.5,  5.0,  7.5,  10.0  and  12.5  cc.  respectively  of  N/50  HCl 
or  NaOH,  then  brought  to  a  volume  of  50  cc.  and  the  hydrogen  ion 
concentration  determined  by  the  use  of  the  Bailey  electrode  and  a 
Leeds  and  Northrup  type  K  potentiometer  in  conjunction  with  an 
N/10  KCl  calomel  electrode  and  a  flowing  junction  of  saturated  KCl. 

Method  for  Determination  of  Gas  Producing  Capacity  of  Flour. 

In  determining  the  gas  producing  capacity  of  a  flour,  twenty  grams 
of  flour  are  weighed  out  and  transferred  to  a  wide  mouthed  bottle. 
To  this  is  added  .5  grams  of  fresh  yeast  suspended  in  20  cc.  of  dis- 
tilled water  and  the  whole  is  thoroughly  stirred  and  the  bottle  stop- 
pered with  a  cork  containing  a  delivery  tube.  The  bottles  are  then 
put  in  a  w^ater  bath  kept  at  37°C.  and  the  liberated  gas  is  measured 
in  an  inverted  cylinder  under  concentrated  brine.  Readings  are  taken 
every  half  hour.  When  malt  extract  is  added  it  is  first  incorporated 
with  the  yeast  and  water  and  added  to  the  flour  in  this  way. 

Baking  Tests. 

The  baking  tests  were  carried  out  according  to  the  standard  formula 
adopted  by  the  American  Instiute  of  Baking  with  one  exception  and 
that  consisted  of  leaving  out  sucrose  in  one  set  of  baking  experiments. 
The  formula  of  the  dough  was  as  follows : 

Flour 325  grams 

Water    173  grams(varied  depending  upon  absorption  of  the  flour) 

Yeast  10  grams 

Sugar  10  grams 

Salt 5  grams 

Lard 6.5  grams 

This  formula  was  corrected  for  the  sugar  content  of  the  malt  flour 
and  malt  extract  used,  the  total  sugar  content  being  always  equivalent 
to  that  stated  in  the  formula.     The  doughs  were  mixed  with  a  small 

24 


bench  mixer,  fermented  and  baked  under  as  accurately  controlled 
conditions  as  possible.  After  the  baked  loaves  were  withdrawn  from 
the  oven  they  were  placed  in  a  cabinet  to  cool  and  were  weighed  1 
hour  after  baking.  The  volumes  of  the  bread  were  taken  the  next 
day  and  each  loaf  was  then  cut  and  judged  for  grain,  texture,  color, 
flavor  and  odor.  In  the  case  where  the  development  of  sugar  forma- 
tion was  followed  during  the  course  of  fermentation,  a  double  portion 
of  dough  was  mixed  and  then  divided.  The  samples  for  anlysis  were 
taken  from  one  portion  of  the  dough  while  the  other  was  baked,  and 
then  judged  as  were  those  described  above.  In  these  experiments 
dough  was  fermented,  with  and  without  yeast,  to  estimate  the  total 
production  of  sugar  and  that  used  by  the  yeast  in  normal  fermenta- 
tion. The  weight  and  temperature  of  the  dough  were  taken  at  stated 
periods  of  fermentation. 

Certain  changes  in  the  hydrophyllic  properties  of  the  gluten  col- 
loids of  this  series  of  doughs,  as  measured  by  the  viscosity  of  dough 
suspensions  in  water,  were  followed  by  Mr.  P.  F.  Sharp,  and  will 
be  reported  by  him  in  a  separate  paper. 

(d)  Influence  of  Varying  Conditions  on  Diastatic  Activity. 
Determination  of  the  Optimum  pH  for  the  Amylase  of  Malt  Flour. 

This  analysis  was  made  to  determine  what  relation  existed  between 
the  optimum  pH  of  dough  and  the  optimum  pH  for  the  maximum 
production  of  maltose  by  the  malt  flour  used.  Sherman  and  his  col- 
laborators determined  the  optimum  pH  for  a  purified  malt  amylase 
and  it  was  thought  of  interest  to  know  how  a  commercial  preparation 
behaved  in  this  regard.  The  process  of  manipulation  varied  slightly 
from  that  described  above  for  the  determination  of  buffer  values,  so 
will  be  described  at  this  time.  Ten  grams  of  malt  flour  containing 
both  the  enzyme  and  the  raw-starch  substrate  were  weighed  out  into 
a  flask.  Enough  water  was  then  added  so  that  when  the  mixture  was 
brought  to  the  desired  pH  by  acid  or  alkali,  the  total  volume  of  liquid 
added  would  be  50  cc.  The  mixture  was  then  digested  for  one  hour 
at  25° C  in  an  accurately  regulated  water  bath.  After  digestion  the 
whole  was  centrifuged  and  25  cc.  (half  of  sample)  was  pipetted  into 
a  200  cc.  volumetric  flask,  2  cc.  of  15%  NagWO^  were  added  and  thor- 
ughly  shaken,  and  20  drops  of  concentrated  HgSO^  is  added  and  made 
up  to  the  mark.  The  preparation  was  centrifuged  again  and  50  cc. 
taken  for  reducing  sugars  as  described  above.  The  other  portion  of 
the  unclarified  extract  was  used  to  determine  the  pH  values. 

The  experimental  data  showing  the  influence  of  diastatic  activity  by 
change  in  pH  are  given  in  Table  VIII  and  illustrated  graphically  in 
Figure  1.     The  optimum  activity  occurred  at  pH=4.26. 

25 


TABLE  VIII. 

Relation  between  hydrogen  ion  concentration  (as  pH)  and  the 

diastatic  activity  of  malt  flour  as  expressed  in  grams  of 

dextrose  per  1.5  grams  of  malt  flour. 


Wt.  of 

Wt.  of 

Normality 

cc. 

CU3O 

Dextrose 

Dextrose- 

of  HCl 

used 

pH 

Grams 

Grams 

Per  Cent 

N/10 

28.0 

1.988 

.1075 

.0527 

3.52 

N/10 

26.0 

2.099 

.1115 

.0548 

3.65 

N/10 

24.0 

2.139 

.1147 

.0563 

3.75 

N/10 

22.0 

2.437 

.1111 

.0545 

3.64 

N/25 

50.0 

2.572 

.1070 

.0525 

3.50 

N/25 

45.0 

2.745 

.1123 

.0552 

3.68 

N/25 

40.0 

2.970 

.1239 

.0611 

4.07 

N/25 

35.0 

3.156 

.1438 

.0714 

4.76 

N/10 

13.0 

3.224 

.1526 

.0759 

5.03 

N/10 

12.0 

3.420 

.1734 

.0868 

5.78 

N/25 

30.0 

3.499 

.1828 

.0917 

6.12 

N/10 

11.0 

3.613 

.1937 

.0976 

6.51 

N/25 

25.0 

3.704 

-      .1935 

.0974 

6.50 

N/25 

22.5 

3.870 

.1984 

.1000 

6.67 

N/25 

20.0 

4.159 

.2238 

.1137 

7.58 

N/25 

15.0 

4.260 

.2305 

.1173 

7.82 

N/25 

12.5 

4.542 

.2224 

.1129 

7.52 

N/25 

10.0 

4.621 

.2190 

.1111 

7.41 

N/25 

5.0 

5.069 

.2081 

.1051 

7.01 

NaOH 

0.0 

5.548 

.1827 

.0917 

6.11 

ff!^f|«[|N/25 

5.0 

6.069 

.1670 

.0834 

5.56 

N/25 

10.0 

6.489 

.1548 

.0769 

5.12 

N/25 

15.0 

6.830 

.1438 

.0713 

4.75 

N/25 

20.0 

7.359 

.1336 

.0661 

4.41 

N/25 

25.0 

7.871 

.1230 

.0605 

4.03 

N/25 

30.0 

8.419 

.1196 

.0589 

3.93 

N/25 

35.0 

8.920 

.1180 

.0581 

3.87 

N/25 

40.0 

9.306 

.1163 

.0572 

3.81 

N/25 

45.0 

9.649 

.1090 

.0535 

3.57 

N/25 

50.0 

9.991 

.1028 

.0503 

3.37 

Influence  of  Time  of  Digestion  on  the  Diastatic  Activity  of  Malt  Flour. 

The  influence  of  time  on  the  activity  of  malt  flour  was  investigated 
to  ascertain  at  what  point,  or  length  of  time,  the  activity  would 
decrease.  Heyl  has  noted  that  at  first  the  reaction  is  logarithmic,  but 
deviates  as  the  products  of  hydrolysis  accumulate.  This  particular 
experiment  was  planned  in  order  to  find  the  optimum  length  of  time 
for  future  periods  of  digestion.  It  developed  that  at  the  end  of  eight 
hours  the  reaction  was  proceeding  at  about  the  same  rate  of  speed 
as  that  of  one  hour  so  it  was  decided  to  make  one  hour  the  standard 
period  of  all  digestions. 

The  effects  of  time  of  digestion  up  to  eight  hours  is  given  in  Table 
IX  and  presented  graphically  in  Figure  2. 


26 


tm 

A. 

r 

\ 

/ 

\ 

/ 

\ 

\ 

/ 

\ 

\  am 

\ 

\, 

, 

\ 

J. 

/ 

\ 

\ 

s. 

OIK 

\ 

/ 

\ 

0U» 

; 

f 

\ 

/S 

/ 

^ 

esx 

/     N 

/ 

1 

1 

Figure  1. 

Effect  of  pH  on  the  activity  of  diastase  in  malt  flour  expressed  as 
grams  dextrose  per  1.5  grams  malt  flour. 

TABLE  IX. 

Effects  of  time  of  digestion  on  diastatic  activity  as  expressed  in  grams 
of  dextrose  per  10  grams  of  malt  flour. 


Wt.  of  Dextrose 

Time  of 

per  10  grams 

Digestion 

Weight  of  CusO 

of  flour 

Dextrose 

Hours 

Grams 

Grams 

Per  Cent 

0.00 

.1112 

.3844 

3.86 

.25 

.1462 

.5128 

5.13 

.50 

.1622 

.5752 

5.55 

1.00 

.1962 

.6992 

7.00 

1.50 

.2230 

.7992 

8.00 

2.00 

.2457 

.8848 

8.85 

3.00 

.2931 

1.0696 

10.70 

4.00 

.3331 

1.2296 

12.30 

5.00 

.3650 

1.3608 

13.61 

6.00 

.3991 

1.5024 

15.03 

7.00 

.4264 

1.6200 

16.20 

8.00 

.4560 

1.7480 

17.48 

27 




/ 

laoiXi 

/ 

/ 

iim 

/ 

/ 

/ 

/looA 

) 

/ 

"^.ooa 

/ 

/ 

f 

i 

1 

0O(H 

/ 

/ 

/ 

(MO 

/ 

] 

i 

/ 

.1000 

/ 

1 

1 

i 

JCOC 

» 

I  3  4-  S 

Time    in  Mourj 


Figure  2. 

Diastatic  activity  as  influenced  by  time  of  digestion,  expressed  in 
grams  of  dextrose  per  10.000  grams  of  malt  flour. 


Effect  of  Temperature  Upon  the  Activity  of  Diastase. 

Practically  all  of  the  work  in  this  investigation  was  carried  out  at 
27°C,  which  is  the  temperature  of  fermentation  used  in  the  bake  shop; 
however,  it  was  necessary  to  find  the  optimum  temperature  of  the 
diastase  in  the  malt  flour,  as  Sherman  notes  that  40*'  is  the  optimum 
temperature  with  a  maximum  at  55 '^  for  pancreatic  amylase.  Most 
of  the  investigators  quoted  above  found  65 °C  to  be  the  optimum  for 
malt  amylase,  while  Swanson  and  Calvin  found  62.5 °C  to  be  the 
optimum  for  wheat  diastase.  It  was  thought  to  be  of  interest  to 
determine  at  what  temperature  the  diastase  in  malt  flour  exerted  its 

28 


UM 

^ 

k,^ 

zm 

/ 

N 

/ 

sm 

/ 

im 

A. 

mIML 

1 

L 

^im 

ZHOU 

1 

L 

/ 

im 

J 

/ 

MX 

/ 

/ 

^ 

y 

' 

^ 

m 

Z5  ■30  ^  ■*0  43  JO  JS  iO  iJ  70 

Tempertiture 

Figure  3. 

Effects  of  temperature  upon  the  activity  of  diastase  in  malt  flour  when 
10.00  grams  are  digested  one  hour  at  various  temperatures. 

TABLE  X. 

Effect  of  temperature  upon  the  activity  of  diastase  in  malt  flour  when 
10  grams  are  digested  for  1  hour  at  various  temperatures. 


Series   1 

Wt.  of 

Series  2 

Wt.of 

Dex- 

Dex- 

Temp. 

trose 

trose 

of 

per  10 

per  10 

Diges- 

Wt. of 

Grams 

Dex- 

Wt.of 

Grams 

Dex- 

tion 

Wt.  of 

Dex- 

Malt 

trose 

Wt.  of 

Dex- 

Malt 

trose 

Degrees 

Cu.O 

trose 

Flour 

Per 

CU2O 

trose 

Flour 

Per 

C 

Grams 

Grams 

Grams 

Cent 

Grams 

Grams 

Grams 

Cent 

27 

.1279 

.0559 

.5590 

5.59 

.1280 

.0559 

.5590 

5.59 

40 

.1951 

.0867 

.8670 

8.67 

.1940 

.0862 

.8620 

8.62 

45 

.2305 

.1034 

1.0340 

10.34 

.2320 

.1041 

1.0410 

10.41 

50 

.2922 

.1333 

1.3330 

13.33 

.2914 

.1329 

1.3290 

13.29 

55 

.4144 

.1960 

1.9600 

19.60 

.4136 

.1956 

1.9560 

19.56 

60x 

.5704 

.2598 

2.5980 

25.98 

.5692 

.2592 

2.5920 

25.92 

65x 

.6030 

.2759 

2.7590 

27.59 

.6018 

.2754 

2.7540 

27.54 

70x 

.5760 

.2626 

2.6260 

26.26 

.5762 

.2627 

2.6270 

26.27 

xAliquots  of  one-half  the  usual  quantity  were  used,  and  the  resulting  values 
multiplied  by  two. 

29 


maximum  effect.  The  procedure  was  as  follows :  10  grams  of  maU 
flour  were  weighed  out  and  digested  at  temperatures  of  27°,  40°,  45*, 
50**,  55°,  60°,  65  ,  and  70  for  one  hour  with  100  cc.  of  water  (previ- 
ously brought  to  temperature).  After  clarifying  and  bringing  to  a 
volume  of  250  cc.  a  25  cc.  aliquot  was  taken  for  reducing  sugars  and 
determined  by  the  Munson  and  Walker  method.  These  data  are 
given  in  Table  X  and  illustrated  graphically  in  Figure  3. 

Effect  of  Concentration  of  Diastase  on  Hydrolysis  of  Starch 
in  Wheat  Flour. 

As  the  concentration  of  diastatic  ferments  added  to  the  dough  is  of 
great  importance,  the  effects  of  different  concentrations  of  malt  flour 
up  to  50%  were  tried  by  mixing  definite  proportions  of  wheat  and 
malt  flour  and  digesting  it  at  27° C.  for  one  hour.  It  was  necessary 
to  first  determine  the  amounts  of  dextrose  formed  when  different 
amounts  of  malt  flour  were  digested  separately  in  order  to  apply  cor- 
rections for  the  autolysis  of  malt  flour  in  the  succeeding  experiments 
with  the  wheat  flour.  This  data  is  given  in  Tables  XI  and  XII,  and 
presented  graphically  in  Figure  4. 


TABLE  XI. 
Autolysis  of  malt  flour  at  27  °C.  for  one  hour. 

Amount  of  Malt  Flour 

used,  grams  0.25  0.50  0.75  1.0  1.25 

Wt.  CuaO.  grams  .0337  .0744  .1080  .1519  .1980 

Wt.  Dextrose,  grams     .0142  .0320  .0469  .0668  .0852 

Dextrose,  per  cent       5.68  6.40  6.25  6.68  6.90 

TABLE  XII. 

Relation  of  concentration  of  malt  flour  to  the  production  of  reducing 
Sugars  from  wheat  flour  when  digested  1  hour  at  27  °C. 


weight  of 

Proportion 

Wt.  of  Cu^O 

Dextrose 

of  wheat 

per  2.S 

formed  per 

flour  to 

2.5  gms. 

malt  flour 

gms.  flour 

flour 

Grams 

Grams 

10:0 
9:1 
8:2 
7:3 
6:4 
5:5 


.0944 
.2167 
.25^3 
.2918 
.3030 
.3279 


.0408 
.0968 
.1168 
.1331 
.1387 
.1512 


Dextrose 
corrected 
for  dex- 
trose of 
malt  flour 
Grams 

.0408 
.0826 
.0848 
.0862 
.0719 
.0760 


Malt 

flour 

Percent 

0.0 
10.0 
20.0 
33.3 
40.0 
50.0 


Dextrose 
formed 
Percent 

1.63 
3.67 
4.24 
4.92 
4.80 
6.06 


30 


it 

_^.    J 

^ 

/ 

sc 

y 

x^ 

^ 

^ 

..  ^ 

^ 

1 

<^ 

i 

/ 

U 

/ 

j.e 

C  iO  20  30  10  St 

fhxeiif  ffe/r  Hour 

Figure  4. 

Relation  of  increasing  concentration  of  malt  flour  to  the  production  of 
reducing  sugars,  when  wheat  flour  is  digested  one  hour  at  27°C. 

Effects  of  Increasing  Amounts  of  Malt  Flour  When  Digested  With  a 
Constant  Quantity  of  Wheat  Flour. 

Table  XII  shows  the  effects  of  large  quantities  of  malt  flour  upon 
wheat  starch,  but  the  amounts  are  out  of  all  proportioii  to  that  used  in 
practice.  In  the  experiments  following,  the  sugar  producing  capacity 
of  the  malt  flour  was  measured  upon  a  series  of  seven  flours  and  a  com- 
mercial wheat  starch  with  concentrations  varying  from  0.2  percent  to 
5.0  percent. 

The  experimental  data  showing  percent  dextrose  produced,  when 
10  grams  of  flour  are  digested  with  0.02  -  0.50  grams  of  malt  flour,  is 
given  in  Table  XIII  and  illustrated  graphically  in  Figure  5. 


31 


TABLE  XIII. 

Percent  dextrose  produced  from  10  grams  of  flours  1001,  1002,  1003, 

1007,  1008,  1009,  1011,  and  a  commercial  wheat  starch  when 

digested  with  0.02  -  0.50  grams  of  malt  flour  for  1  hour 

at  27  °C. 


ri 

our  ;:3arn 

pie  iNumoer  — 

L.om- 
mercial 

Malt  Flour 

1001 

1002 

1003 

1007 

1008 

1009 

1011 

Wheat 

Used 

Starch 

Grams 

Jc 

% 

% 

% 

% 

% 

% 

% 

% 

.0000 

0.00 

1.85 

1.34 

.40 

.94 

2.28 

1.36 

.18 

.0200 

.20 

2.35 

1.72 

.0250 

.25 

2.15 

1.50 

.74 

1.15 

.32 

.0400 

.40 

1.80 

.0500 

.50 

2.32 

1.64 

.88 

1.71 

2.38 

.85 

.42 

.0600 

.60 

1.95 

.0750 

.75 

2.47 

1.74 

1.03 

2.04 

2.48 

.50 

.0800 

.80 

1.98 

.1000 

.99 

2.59 

1.85 

1.09 

2.10 

2.54 

2.12 

1.00 

.59 

.1200 

1.19 

2.19 

.1250 

1.24 

2.69 

1.94 

1.14 

2.32 

1.06 

.62 

.1500 

1.48 

2.77 

2.04 

1.20 

2.50 

2.56 

2.28 

1.14 

.69 

.1750 

1.72 

2.58 

2.46 

1.16 

.2000 

1.96 

2.90 

2.11 

1.36 

2.80 

2.62 

2.62 

1.47 

.84 

.2250 

2.20 

2.64 

.2500 

2.44 

3.02 

2.21 

1.40 

2.95 

2.63 

2.67 

1.51 

.91 

.3000 

2.91 

3.15 

2.31 

1.49 

3.21 

2.72 

2.84 

1.56 

1.07 

.4000 

3.84 

3.34 

2.48 

1.64 

3.35 

2.83 

3.06 

1.72 

.5000 

4.76 

3.47 

2.61 

1.73 

2>.1Z 

3.03 

3.24 

1.93 

1.53 

The  Production  of  Reducing  Sugars  in  the  Dough  During 
Fermentation. 

The  production  of  reducing  sugars  in  an  actively  fermenting  dough 
and  its  subsequent  use  by  the  yeast  was  followed  at  various  stages  of 
fermentation  This  necessitated  running  two  parallel  doughs,  one 
having  the  required  amount  of  yeast,  while  the  other  had  no  yeast 
added  but  identical  in  every  other  respect.  After  mixing  the  dough,  a 
ten  gram  sample  was  pinched  off,  shaken  to  a  homogeneous  suspen- 
sion, clarified  and  the  reducing  sugars  determined.  At  stated  periods 
10  gram  samples  were  taken  and  submitted  to  analysis,  as  after  the 
mix.  Twice  the  usual  quantity  of  each  dough  (with  and  without 
yeast)  was  mixed,  divided  into  two  equal  parts  and  the  samples  taken 
from  one  portion  only  in  order  to  have  one  dough  to  bake  in  the 
usual  way. 

32 


40 

dS 

X 

^ 

^ 

«w 

JO 

jt 

^<^ 

1^ 

^^ 

MAS 

'^ / 

^ 

^ 
X 

^ 

li 

J 

X 

A 

^ 

MM 

<^ 

/ 

7 

/ 

^ 

■^ 

■*. 

/ 

y 

'/ 

^ 

1 

/.s 

( 

fy 

/ 

^ 

^ 

mi 

Y 

^^^ 

^ 

Hoi-' 

y 

^ 

^ 

^^ 

,^' 

m 

/• 

><; 

^ 

^. 

X^ 

^^ 

,-^ 

/ 

K 

^^ 

r^ 

y'^ 

Ai 

/ 

,^ 

i^ 

/ 

y 

CO 

Y 

0  OS        JO  li        JO         23         JO         JS         .40  *S        M 

Gramj  Malt  Flour 

Figure  5. 

Percent  of  dextrose  formed  from  a  series  of  flours  when  digested  one 
hour  at  27  ^'C.  with  various  amounts  of  malt  flour. 

Tables  XIV-XXII  give  this  data  on  three  flours  representing  a 
strong  type  Canadian  patent  flour  (1008),  a  decidedly  weak  Pacific 
Coast  patent  flour  (1003),  and  a  clear  flour  from  Kansas  (1002).  Each 
flour  was  mixed  with  varying  amounts  of  diastatic  preparations  as  fol- 
lows. 1.5  percent  malt  flour,  4.0  percent  malt  flour  and  3.0  percent 
malt  extract.  Controls  with  no  diastase  were  included  in  each  series. 
No  sugars  were  added  to  any  of  the  doughs  except  that  amount  con- 
tained in  the  malt  flour  and  malt  extract  used,  but  this  amount  was 
deemed  negligible  in  its  effect  upon  frementation. 

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Productions  of  reducing  sugars  in  the  panary  fermentation  of  flour 
1008  with  different  concentrations  of  malt  flour  and  malt   extract. 
(Full  lines  indicate  doughs  to  which  yeast  was  added,  dotted  lines  no 
yeast  dough). 


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Figure  7. 
Production  of  reducing  sugars  in  the  panary  fermentation  of  flour 
1003  with  different  concentrations  of  malt  flour  and  malt  extract. 
(Full  lines  indicate  doughs  to  which  yeast  was  added,  dotted  lines 
no  yeast  dough). 

40 


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Figure  8. 

Productions  of  reducing  sugars  in  the  panary  fermentation  of  flour 
1002,  with  different  concentrations  of  malt  flour  and  malt  extract. 
(Full  lines  indicate  doughs  to  which  yeast  was  added,  dotted  lines 
no  yeast  dough). 


Determination  of  Proteolytic  Activity  as  Measured  by  the  Fall  in  Vis- 
cosity of  Flour-water  Suspensions,  when  Digested  with 
Diastatic  Preparations. 

The  action  of  proteolytic  ferments  upon  gluten  is  accompanied  by 
a  breaking  down  of  the  protein  material  into  simpler  compounds  sr.ch 
as  protesoses,  peptones  and  amino  acids.  As  the  latter  can  be  easily 
measured  by  the  amount  of  free  amino  nitrogen,  it  was  thought  th^t 
an  increase  in  amino  nitrogen  measured  by  VanSlyke's  method,  would 
be  a  measure  of  the  amount  of  proteolysis  taking  place.  This,  how- 
ever, was  not  the  case  as  no  appreciable  difference  in  amino  nitrogen 
could  be  detected  when  the  flour  was  digested  with  and  without  malt 
preparations. 

41 


It  is  well  known  that  dough  becomes  slack  or  less  viscous  during 
the  fermentation  period.  This  has  been  attributed  to  the  action  of  the 
proteolytic  enzymes  of  the  yeast  and  partially  to  those  in  malt  prep- 
arations. Ford  and  Guthrie  were  unable  to  demonstrate  proteolytic 
enzymes  in  flour  by  means  of  the  viscosimeter  and  concluded  that  any 
which  were  present  would  have  little  or  no  effect  upon  the  gluten  dur- 
ing fermentation.  Sharp  and  Gortner  have  shown  that  the  hydration 
capacity  and  the  quality  of  the  gluten  can  be  accurately  determined  by 
the  use  of  the  viscosimeter.  They  have  shown  that  the  viscosity  of  a 
flour-water  suspension  is  tremendously  increased  and  increases  to  a 
well  defined  maximum  by  the  addition  of  lactic  acid  in  small  amounts, 
while  the  further  addition  of  lactic  acid  causes  no  appreciable  change 
in  viscosity  value.  The  suspensions  of  various  flours  in  water  dif- 
fered slightly  in  initial  viscosity  and  it  was  only  after  the  addition  of 
the  lactic  acid  that  these  differences  were  increased  to  such  an  extent 
as  to  make  the  results  of  significance.  Under  the  conditions  of  Sharp 
and  Gortner's    experiments  the  addition  of  5  cc  N/1  lactic  acid  was 


TABLE  XXV. 

The  measurements  of  proteolytic  activity  in  a  flour-water  suspension 

showing  the  effects  of  different  periods  of  digestion  (1-5  hours) 

at  30  °C.  with  100  cc  of  water  and  concentrations  of  malt  flour 

(2  and  4  percent)   on  viscosity  (degrees  MacMichael) 

with  the  addition  of  various  amounts  of 

lactic  acid. 

Viscosity  in  degrees  MacMichael  on  addition  of  N/1  lactic  acid. 
Nl  Lactic  Acid 

added  cc 0.0  0.5  1.0  1.5  2.0  3.0  5.0 

Malt 
Flour 
Digestion  used        Degr's  Degr's     Degr's       Degr's     Degr's       Degr's        Degr's 
Hours    Percent        M  M  M  M  MM  M 


1 

0.0 

33 

83 

119 

134 

144 

152 

160 

2 

0.0 

41 

107 

139 

151 

156 

161 

167 

3 

0.0 

36 

86 

120 

133 

139 

148 

156 

4 

0.0 

38 

86 

117 

129 

136 

144 

160 

5 

0.0 

34 

83 

115 

127 

133 

141 

153 

1 

2.0 

35 

86 

126 

135 

141 

147 

151 

2 

2.0 

29 

70 

101 

115 

122 

130 

135 

3 

2.0 

29 

67 

96 

108 

116 

122 

127 

4 

2.0 

30 

69 

97 

106 

112 

118 

122 

5 

2.0 

31 

70 

95 

104 

109 

115 

120 

1 

4.0 

32 

71 

104 

119 

127 

134 

138 

2 

4.0 

25 

57 

88 

101 

109 

117 

121 

3 

4.0 

22 

51 

n 

90 

97 

105 

111 

4 

4.0 

24 

48 

n 

83 

88 

96 

100 

5 

4.0 

22 

45 

68 

77 

83 

90 

96 

42 


sufficient  to  bring  any  flour  to  the  point  of  highest  viscosity ;  accord- 
ingly their  method  was  followed  to  see  whether  any  differences  could 
be  detected  when  flour  was  digested  alone  and  when  digested  with 
malt  preparations  and  if  any  differences  which  existed  in  the  flour- 
water  extracts  could  be  increased  by  the  addition  of  lactic  acid. 

A  few  preliminary  experiments  in  which  flour  was  digested  with  and 
without  malt  preparations  for  different  periods  of  time  showed  that 
the  flour-water  suspensions  of  the  different  flours  varied  very  little  in 
their  initial  viscosities,  thus  showing  why  Ford  and  Guthrie  were  un- 
successful in  measuring  proteolysis  by  means  of  the  viscosimeter. 
With  the  addition  of  lactic  acid,  however,  great  differences  were  notice- 
able between  the  different  flours  and  the  results  justified  the  following 
experiments. 


1 — 

m 

Mi 

c^ 

\ 

M 

—  - 

y 

^ 

\ 

s 

\ 

^ 

\ 

\ 

AS 

I 

N 

1  -.I 

\ 

4 

Jl     At 

> 

\ 

\ 

ft    n 

\ 

\ 

1,. 

\ 

\ 

\ 

\ 

\ 

s. 

J  J 

\ 

< 

^ 

. 

MS 

\ 

M 

\ 

s 

M 

\ 

Mt 

\ 

— 

» 



^ 

-^ 

/  2  ^ 

Time  ef  Dioeition  in  Houry 


Figure  9. 

Effect  of  the  proteolytic  enzymes,  contained  in  malt  flour,  upon 
wheat  flour  as  measured  by  the  fall  in  viscosity  when  digested  1  to  5 
hours  at  30 °C.     With  lactic  acid  added. 


43 


The  effect  of  time  of  digestion  was  first  tried  to  determine  the  op- 
timum time  of  digestion.     The  experiment  consisted  of  digesting  flour 

1001  (a  strong  Kansas  patent)  for  1  to  5  hours  with  100  cc  of  water, 
and  repeating  with  the  same  flour  after  adding  2  and  4  percent  of  malt 
flour.  After  digesting  for  the  stated  period  of  time  the  flour-water 
suspensions  were  transferred  to  the  cup  of  the  MacMichael  viscosi- 
meter  and  the  average  of  three  readings  taken,  N/1  lactic  acid  was  then 
added  in  small  amounts  up  to  5  cc.  The  mixture  was  thoroughly 
stirred  after  each  addition  of  acid  and  the  average  of  three  viscosity 
readings  taken. 

The  experimental  data  of  this  series  when  digested  at  30°  C.  is  given 
in  Table  XXV  and  the  data  in  the  last  column  of  this  Table  is  shown 
graphically  in  Figure  9. 

It  appears  from  this  table  that  four  hour  digestion  is  ample  time  to 
secure  evidence  of  proteolytic  action,  and  this  time  of  digestion  was 
used  in  all  subsequent  work.  Also  the  temperature  of  digestion  was 
increased  from  30°  to  40°  in  order  to  procure  greater  activity  of  the 
enzymes. 

The  data  given  in  Table  XXVI  and  illustrated  graphically  in  Figure 
10  was  obtained  by  digesting  a  series  of  flours  (1001-1002-1003-1007 
and  1008)  with  varying  amounts  of  malt  flour  (1.0-1.5-2.0-2.5-3.0  and 
4  percent)  with  100  cc  of  water  at  40° C.  and  determining  the  viscosity 
after  adding  5  cc  of  N/1  lactic  acid.  Table  XXVII  and  Figure  lOA 
show  similar  data  when  malt  extract  was  used. 

It  has  been  shown  in  the  literature  cited  that  even  minute  traces  of 
salts  have  a  marked  affect  upon  the  imbibition  capacities  of  gluten. 
It  was,  therefore,  thought  advisable  to  see  how  the  viscosity  of  the 
flour  reacted  when  treated  as  above  but  with  the  salts  of  the  flour  and 
malt  flour  washed  out  after  the  digestion  period.  The  precedure  was 
as  follows :  The  equivalent  of  18  grams  of  water-free  flour  1002,  was 
weighed  into  each  of  six  flasks  and  digested  with  0.0,  1.0,  1.5,  2.0,  2.5, 
3.0  and  4.0  percent  malt  flour  in  100  cc  of  water  at  40° C.  After  four 
hours  900  cc  of  distilled  water  were  added,  the  whole  well  shaken  and 
centrifuged.  The  supernatant  liquid  was  decanted  and  the  flour 
residue  shaken  up  with  water  and  after  complete  disintegration  made 
up  to  100  cc,  placed  in  viscosimeter  cup,  and  the  readings  taken  after 
adding  varying  amounts  of  lactic  acid. 

The  data  showing  the  viscosity  in  the  presence  of  lactic  acid  of  flour 

1002  with  the  salts  washed  out  is  given  in  Table  XXVIIL 

In  order  to  demonstrate  still  further  that  the  salt  content  of  the 
added  malt  flour  did  not  vitiate  the  results  obtained  in  Table  XXVI 
when  flour  (for  example)  1002  was  digested  4  hours  with  4  percent 

44 


TABLE  XXVI. 


EflFect  of  varying  amounts  of  malt  flour  upon  the  viscosity  of  18  grams 

(calculated  on  the  dry  basis)  of  wheat  flour  when  digested  for 

four  hours  at  40 °C.  with  100  cc  of  water  (5  cc  N/1  lactic 

added  in  each  instance).    Viscosity  readings  in 

degrees  MacMichael. 

%  Malt  I  (J 

Flour  Used 0.0           1.0  1.5             2.0            2.5  3.0 

Degr's  Degr's  Degr's  Degr's      Degr's  Degr's 

Flour  No.             M            M  M              M              M  M 


1001 
1002 
1003 
1007 
1008 


145 

150 

50 

124 

151 


123 
126 
H 
106 
136 


119 
118 
42.5 
103 
129.5 


114 
109 

40 

95 
117.5 


112 

97 

36.5 

97 
112 


105 

99 

37 

103 

109 


4.0 

Degr's 

M 


93 

81 

28 

88 

102 


IS) 

*x 

\, 

/* 

\ 

fit 

\\ 

\ 

fJi 

\ 

\;^ 

<> 

}' 

\ 

A, 

N 

*'"*-.. 

^•/r 

\ 

\ 

\-- 

^^ 

1- 

\ 

S 

^\ 

\ 

\ 

\, 

s 

\ 

^ 

V 

^.u-. 

\ 

N, 

4  ,,. 

\ 

s. 

\ 

^ 

N 

'\ 

\ 

w 

\ 

s 

\^ 

N 

\ 

HX 

X 

\ 

\, 

\, 

« 

^^ 

^ 

^ 

10 

\ 

\^ 

\ 

* 

\ 

^ 

s 

« 

t 

i 

J 

4 

' 

Kr^^nt  M^lt  J^tpwmtftn   UitJ 


Figure  10. 


Changes  in  viscosity  of  flour  water  suspensions  when  digested  4 
hours  at  40  °C.  with  increasing  amounts  of  malt  flour  and  malt  extract, 
as  measured  in  degrees  MacMichael  with  lactic  acid  added.  (Full 
line  curves  flours  digested  with  malt  flour,  dotted  line  curves  those 
digested  with  malt  extract). 


45 


TABLE  XXVII. 


Effect  of  varying  amounts  of  malt  extract  upon  the  viscosity  of  18 

grams  (calculated  to  the  dry  basis)  of  wheat  flour  when  digested 

4  hours  at  40  C.  with  100  cc  of  water.     (5  cc  of  N/1  lactic 

acid  added  in  each  instance).    Viscosity  readings 

in  degrees  MacMichael. 


%  Malt 
Ext.  Used. 

Flour  No. 

1002 
1003 
1008 


...0.0     1.0 
Degr's  Degr's 
M     M 


145 

57 

150 


136 

51 

138 


1.5 

Degr's 

M 

131 

50 

134 


2.0 

Degr's 

M 

127.5 
48 
132 


2.5 
Degr's 
M 

120.5 
43 
127 


3.0 

Degr's 

M 

111 

38 

122 


4.0 
Degr's 
M 

106 

34 

112 


too 

(K 

4 

L 

5 

^- 

^     X 

^■- 

"^v 

m 

^\ 

^^ 

^ 

\ 

^ 

""••. 

jU 

N 

— \- 

-..^ 

•»». 

Jl 

-"V, 

\ 

■  ---, 

fi 

N 

Tin,enf  McJT  PreporaTion  Used 

Figure  10-A. 

Changes  in  viscosity  of  water  suspensions  of  flour  1003  when 
digested  4  hours  at  40°  with  increasing  amounts  of  malt  flour  and 
malt  extract,  as  measured  in  degrees  MacMichael.  With  lactic  acid 
added.  (Full  line  curve  digestions  with  malt  flour,  dotted  line  curve 
digestion  with  malt  extract). 


46 


411 

405 

328 

340 

312 

315 

295 

305 

263 

271 

malt  flour  three  samples  of  1002  were  weighed  out,  two  were  used  as 
checks  and  to  the  third  4  percent  malt  flour  was  added.  At  the  end 
of  three  and  one-half  hours  4  percent  malt  flour  was  added  to  ore  of 
the  checks  and  the  mixture  well  shaken.  At  the  end  of  4  hours  diges- 
tion, the  viscosities  of  all  three  preparations  were  determined  as  usual. 
The  data  showing  the  viscosities  of  this  experiment  are  given  in 
Table  XXIX,  and  leave  no  doubt  but  that  proteolysis  has  taken  place. 

TABLE  XXVIII. 

The  effect  on  the  viscosity  of  flour  1002  with  the  salts  washed  out  af- 
ter digesting  with  varying  amounts  of  malt  flour  for  4  hours  at 
40 °C.  with  100  cc  of  water  (lactic  acid  added  in  each 
instance.) 

Lactic  Acid  cc.                      0.5  cc.  1.0  cc                           1.5  cc. 

Viscosity  Viscosity                      Viscosity 

Percent                           Degrees  Degrees                        Degrees 

Malt  Flour                             M  MM 

0  388 

1  299 

2  295 

3  273 

4  245 


TABLE  XXIX. 

Effect  of  three  and  one-half  hour  digestion  without,  and  half  an  hour 

digestion  with  malt  flour  as  compared  to  a  4  hour  digestion  with 

and  without  4  percent  malt  flour  upon  the  viscosity  of 

suspensions  in  water. 

Cubic  Centimeters  N/1  Lactic  Acid  Added  0.0  5.0 

Flour  No.  Degrtts        Degrees 

1002       digested  without  malt  flour 38  145 

1002       digested  with  4%  malt  flour 19  81 

1002       digested  3.5  hrs.  without  and  3  minutes  with 

4%  malt  flour 30  127 

Gas  Production  Capacity  of  Wheat  Flour  in  Relation  to  Strength. 

Although  Wood  pointed  out  that  the  gas  production  capacity  of  a 
flour  was  an  index  to  one  of  the  factors  in  flour  strength  and  Baker 
and  Hulton  pointed  out  that  weak  flours  were  low  in  liquifying  en- 
zymes, they  did  not  submit  sufficient  data  to  show  that  this  was  ac- 
tually the  case.  In  the  following  work  the  gas  producing  capacities 
of  a  series  of  flours  was  determined,  according  to  the  method  of  Wood, 
and  with  and  without  the  addition  of  malt  extract.  The  flours  selected 
consisted  of  two  typically  strong  patent  flours  1008  and  1009,  two  clear 
flours  of  fair  baking  strength  1002  and  1007,  and  one  typically  weak 

47 


patent  flour  1003,  milled  from  Washington  wheat.  The  method  fol- 
lowed was  the  same  as  that  described  in  the  methods  under  gas  pro- 
duction. 

The  data  giving  the  cubic  centimeters  of  gas  produced  from  flours 
1002,  1003,  1007,  1008  and  1009  when  fermented  with  and  without  the 
addition  of  1  percent  malt  extract,  is  given  in  Table  XXX,  and  illus- 
trated graphically  in  Figures  11  and  12. 

TABLE  XXX. 

Effect  of  added  malt  extract  upon  the  gas  producing  capacity  of  flours 

1002,  1003,  1007,  1008  and  1009  when  fermented  with  2.5  percent 

yeast  for  four  hours  at  35°. 


No  Add( 

id  Malt  Extract 

One  Percent  Malt  Extract 

Flour  No 

.  1002 

1003 

1007 

1008 

1009 

1002 

1003 

1007 

1008 

1009 

Time  of 

Fermentation 

Gas 

Gas 

Gas 

Gas 

Gas 

Gas 

Gas 

Gas 

Gas 

Gas 

Hours 

cc. 

cc. 

cc. 

cc. 

cc. 

cc. 

cc. 

cc. 

cc. 

cc. 

0.5 

13 

14 

10 

10 

7 

14 

15 

12 

14 

8 

1.0 

34 

33 

31 

27 

28 

35 

34 

33 

36 

31 

1.5 

62 

57 

58 

53 

60 

64 

59 

60 

66 

61 

2.0 

98 

80 

92 

90 

99 

88 

94 

105 

101 

2.5 

140 

95 

132 

148 

116 

141 

115 

134 

153 

125 

3.0 

177 

104 

174 

202 

148 

180 

140 

178 

203 

153 

3.5 

214 

117 

212 

250 

176 

218 

184 

223 

252 

181 

4.0 

245 

123 

243 

192 

254 

196 

270 

196 

4.5 

. 

128 

208 

TABLE  XXXL 

Changes  in  pH  during  the  fermentation  of  the  dough  with  values  for 

flour  extract  and  the  extract  of  bread  crumb. 

Baking  Data. 


pH  Values 

Flour 

Ash 

Flour 

Mix 

1st  Pch. 

2nd  Pch. 

3rd  Pch. 

After  Pf. 

Bread 

No. 

% 

1001 

.40 

5.81 

5.33 

5.18 

5.09 

5.02 

4.79 

4.96 

1002 

.61 

6.05 

5.65 

5.25 

5.25 

5.24 

5.05 

5.29 

1003 

.46 

6.00 

5.24 

5.16 

5.19 

5.37 

5.05 

5.16 

1004 

.83 

6.17 

5.91 

5.92 

5.87 

5.85 

5.80 

5.52 

1005 

.43 

5.84 

5.75 

5.40 

5.22 

5.23 

5.17 

5.29 

1006 

.38 

5.78 

5.70 

5.2& 

5.22 

5.17 

5.03 

5.3U 

1007 

.64 

6.10 

5.76 

5.63 

5.58 

5.59 

5.53 

5.58 

1008 

.42 

5.98 

5.33 

5.23 

5.17 

5.19 

5.25 

1011 

.56 

6.15 

5.47 

5.33 

5.30 

5.20 

4.92 

5.28 

Change  in  Hydrogen  Ion  Concentration  of  Fermenting  Dough. 

As  considerable  data  has  been  accumulated  upon  this  series  of  flours 
it  was  thought  that  the  changes  in  hydrogen  ion  concentration  dur- 
ing the  fermentation  period  would  be  of  considerable  value,  inasmuch 
as  the  speed  of  diastatic  and  proteolytic  activity  is  influenced  to  such  a 
great  degree  by  changes  in  hydrogen  ion  concentration  and  many  ir- 


48 


■XK 

tsi 

f 

/ 

/ 

/ 

^ 

/ 

/ 

^ 

1 

//j 

/ 

i 

//. 

y 

i 



§9 

^ ... 

■  -" 

-'"" 

/ 

.•''"' 

JD 

.(< 

f 

./( 

f 

0 

^ 

r1 

Time  in  Hours 

Figure  11. 

Gas  producing  capacity  of  flours  1002,  1003,  1007,  1008  and  1009, 

fermented  with  2.5%  yeast. 


Joo 

m 

I 

/ 

too 

i 

// 

^ 

8" 

A 

/  ^ 

^ 

^  ISO 

// 

'  / 

A 

^ 

i. 

^ 

/ 

JO 

/ 

^ 

A 

/ 

0 

^ 

^ 

Time  in  Hoon 

Figure  12. 
Effect  of  1.%  added  malt  extract  upon  the  gas  producing  capacity  of 
flours  1002,  1003,  1007,  1008  and  1009,  when  fermented  with  25.%  yeast. 

49 


regularities  in  the  data  might  be  accounted  for  in  this  manner.  The 
activity  of  yeast  is  also  vfery  much  influenced  by  changes  in  the  pH  of 
its  medium.  The  doughs  were  made  from  the  same  flours  and  in  the 
same  manner  as  that  reported  in  the  section  on  reducing  sugars 
formed  during  fermentation.  The  procedure  consisted  of  taking  10 
grams  of  dough  and  shaking  it  up  with  50  cc  of  water  until  a  homo- 
geneous suspension  was  secured.  The  whole  was  then  centrifuged 
and  the  pH  of  the  supernatant  liquid  was  then  determined  in  the  man- 
ner described  above.  Samples  were  taken  at  the  mix,  first  punch, 
second  punch,  third  punch  and  after  proof.  The  pH  value  of  the  flour 
extract  is  also  given  as  is  that  of  a  water  extract  of  the  finished  bread. 
The  data  is  shown  in  Table  XXXI. 

In  the  past  all  chemical  and  physical  data  accumulated  on  the 
strength  of  flour  has  been  accompanied  by  baking  tests  which  in  the 
final  analysis  have  been  the  criterion  of  flour  strength.  Inasmuch  as  it 
was  imperative  to  have  accurate  knowledge  of  the  flours  and  the  ef- 
fects of  diastatic  ferments,  a  series  of  baking  tests  was  conducted  in  ad- 
dition to  the  baking  tests  made  in  studying  formation  of  reducing 
sugars  and  the  change  in  hydrogen  ion  concentration  during  the  fer- 
mentation process.  All  baking  tests  were  conducted  as  nearly  alike  as 
possible  to  secure  comparable  data. 

In  the  baking  experiments  conducted  to  test  the  effects  of  added 
diastatic  ferments  upon  wheat  flours,  the  two  diastatic  preparations 
used  throughout  the  entire  work  were  employed,  namely  a  malt  flour 
and  a  malt  extract.  These  were  added  in  amounts  of  .5,  1.0,  1.5,  2.0, 
2.5,  3.0  and  4  per  cent  to  each  of  a  series  of  flours  and  the  results  are 
recorded  as  total  time  of  fermentation,  valume  of  the  loaf,  color,  grain 
and  texture  of  the  crumb,  flavor  and  odor.  The  doughs  were  made  in 
the  manner  described  under  the  methods  of  baking  tests  and  where 
fermentation  is  spoken  of,  total  fermentation  is  meant  including  both 
the  actively  fermenting  and  proofing  periods. 

The  data  showing  the  effects  of  varying  amounts  of  malt  flour  and 
malt  extracts  upon  flours  1001,  1002,  1003,  1007,  and  1008  is  given  in 
tables  XXXII  to  XLI. 

TABLE  XXXII. 
The  effects  of  varying  amounts  of  malt  flour  upon  the  baking  qualities 

of  flour  1001. 

Malt  Flour  %  Standard     .5  1.0        1.5        2.0         2.5        3.0         5.0 

Fermentation  Hrs.  5:00  4:56  4:52  4:48  4:44      4:40  4:36  4:32 

Sucrose  added  gms.  10.00  9.790  9.580  9.370  9.155  8.940  8.730  8.310 

Wt.  of  dough  gms.  513  515  516        517  517      521        522  525 

Wt.  of  loaf  gms.  454  452  443        446  450      446        459  457 

Vol  of  loaf  cc.  1870  1890  2020  1955  2030    2060  1910  2010 

50 


General  Remarks :  Loaves  grade  down  with  respect  to  grain  and 
texture  with  each  added  increment  of  malt  flour.  Color  of  the  crumb 
is  markedly  influenced  by  each  increase  of  malt  flour.  The  crumb  was 
full  of  large  gas  holes  which  was  probably  due  to  localized  yeast  ac- 
tivity. Mean  average  temperature  of  fermentation  was  81**F.,  and  the 
temperature  of  baking  440°  F.     Time  of  baking  26  minutes  . 

TABLE  XXXIII. 

The  effects  of  varying  amounts  of  malt  extract  upon  the  baking  qual- 
ities of  flour  1001. 


Malt  Extract  % 

Standard     .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 

5:00      4:52 

4:48 

4:44 

4:38 

4:34 

4:30 

4:26 

Sucrose  added  gms. 

10.00      8.94 

7.88 

6.820 

5.76 

4.70 

3.64 

1.52 

Wt.  of  dough  gms. 

513        514 

514 

515 

516 

514 

515 

517 

Wt.  of  loaf  gms. 

454        457 

450 

448 

447 

450 

453 

457 

Vol.  of  loaf  cc. 

1870      1810 

1880 

1895 

1925 

1920 

1970 

1880 

General  Remarks :  The  texture  and  grain  was  excellent  through- 
out, but  the  loaf  made  with  1  percent  malt  extract  seemed  to  have 
better  grain  than  any  other.  Color  was  very  good  up  to  3  percent  of 
malt  extract  where  increase  in  the  malt  extract  darkens  the  color,  or 
shade.  The  volume  of  the  loaf  also  increases  up  to  3  percent  malt 
extract  and  then  drops.  A  very  decided  sweet  honeyed  flavor  was  im- 
parted to  the  bake  which  grew  more  pronounced  as  the  percentage  of 
malt  extract  increased.  Mean  temperature  of  fermentation  81** -82°. 
Time  of  baking  25  minutes.     Temperature  of  baking  440°-430°C. 

TABLE  XXXIV. 

The  effects  of  varying  amounts  of  malt  flour  upon  the  baking  qaulities 

of  flour  1002. 


Malt  Flour  % 

Standard     .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 

5:18      5:13 

5:08 

5:03 

4:58 

4:53 

4:48 

4:44 

Sucrose  added  gms. 

10.00      9.79 

9.58 

9.37 

9.155 

8.94 

9.73 

8.31 

Wt.  of  dough  gms. 

519        523 

525 

528 

529 

530 

532 

535 

Wt.  of  loaf  gms. 

454        451 

454 

451 

460 

458 

470 

471 

Vol.  of  loaf  cc. 

1740      1890 

2040 

2010 

2050 

2010 

2050 

2030 

General  Remarks :  Color  of  crumb  grades  down  very  quickly  with 
each  addition  of  malt  flour.  Grain  very  much  alike  throughout  while 
texture  was  even.  Color  of  the  crust  improves  with  increase  in  matt 
flour ;  very  good  smell  and  good  taste  while  malt  flavor  is  not  in  evi- 
dence. Mean  Temperature  of  fermentation  82° -83°  and  baking  470° F. 
Time  of  baking  24  minutes. 

51 


TABLE  XXXV. 
The  effect  of  varying  amounts  of  malt  extract  upon  the  baking  qual- 
ities of  flour  1002. 

Malt  Extract  %  Standard     .5  1.0        1.5        2.0         2.5        3.0         5.0 

Fermentation  Hrs.  5:19  5:12  5:07  5:02  4:57  4:52  4:47  4:42 

Sucrose  added  gms.  10.00  8.94  7.88  6.82  5.76  4.70  3.64  1.52 

Wt.  of  dough  gms.  519  514  513  513  513  514  515  521 

Wt.  of  loaf  gms.  454  441  448  445  437  436  440  447 

Vol.  of  loaf  cc.  1740  1900  2050  2010  2010  1980  1960  1940 

General  Remarks :  Color  of  crumb  grades  off  a  trifle  as  percentage 
of  malt  extract  increases.  Texture  increases  in  fineness  with  increase 
in  malt  extract.  Grain  is  decidedly  improved  with  an  addition  of  malt 
extract  up  to  2  percent  and  then  falls  off.  Odor  and  flavor  of  malt  ex- 
tract increases  as  the  percentage  of  malt  extract  increases.  No  no- 
ticeable difference  in  the  color  of  the  crust  between  the  various  bakes. 
Mean  temperature  of  fermentation  82°-83°  and  baking  479°F.  Time 
of  baking  25  minutes. 

TABLE  XXXVI. 
The  effect  of  varying  amounts  of  malt  flour  upon  the  baking  qualities 

of  flour  1003. 

Malt  Flour  %  Standard     .5  1.0        1.5        2.0         2.5        3.0         5.0 

Fermentation  Hrs.  4:42  4:38  4:34  4:28  4:24  4:20  4:16  4:12 

Sucrose  added  gms.  10.00  9.79  9.58  9.37  9.155  8.94  8.73  8.31 

Wt.  of  dough  gms.  511  512  515  515  513  514  521  523 

Wt.  of  loaf  gms.  468  467  468  464  457  463  469  476 

Vol.  of  loaf  cc.  1660  1760  1675  1860  1710  1690  1650  1550 

General  Remarks :  Standard  loaf  had  by  far  the  best  color,  which 
grades  down  very  quickly  with  increase  in  malt  flour.  Loaf  made 
with  0.5  percent  malt  flour  possessed  the  best  texture,  flavor  and  odor. 
That  with  1  percent  malt  flour  had  the  best  grain  and  those  loaves  with 
increased  quantities  grade  off  to  a  very  coarse  grain.  Loaves  were 
soggy  and  heavy.  Mean  temperature  of  fermentation  was  81°  and 
that  of  baking  470°  F.     Time  of  baking  21  minutes. 

TABLE  XXXVIL 
The  effects  of  varying  amounts  of  malt  extract  upon  the  baking  quali- 

ities  of  flour  1003. 


Malt  Extract  % 

Standarc 

I    .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 

4:42 

4:44 

4:40 

4:36 

4:32 

4:28 

4:25 

4:21 

Sucrose  added  gms. 

10.00 

8.94 

7.88 

6.82 

5.76 

4.70 

3.64 

1.52 

Wt.  of  dough  gms. 

511 

504 

507 

504 

506 

508 

.  508 

492 

Wt.  of  loaf  gms. 

468 

460 

461 

454 

448 

453 

460 

448 

Vol.  of  loaf  cc. 

1660 

1730 

1775 

1810 

1770 

1700 

1750 

1680 

52 


General  Remarks :  Color  was  decidedly  the  best  in  the  loaf  made 
with  0.5  percent  malt  extract  while  the  texture  and  flavor  were  best  in 
that  with  2.5  percent.  Best  grain  was  secured  when  1.5  percent  malt 
extract  was  used  and  seemed  to  run  off  as  percent  malt  extract  in- 
creased but  nearly  as  bad  as  that  of  the  malt  flour.  The  malt  flavor 
was  not  as  pronounced  as  in  the  previous  bakes  when  using  malt  ex- 
tract. Color  of  crust  good  throughout.  Mean  temperature  of  fer- 
mentation 81°  and  that  of  baking  525°F.     Time  of  baking  20  minutes 

TABLE  XXXVIII. 

The  effect  of  varying  amounts  malt  flour  upon  the  baking 

qualities  of  flour  1007. 

Malt  Flour  %  Standard     .5  1.0         1.5         2.0         2.5         3.0         5.U 

Fermentation  Hrs.  5:22      5:15       5:10      5:06      5:02      4:58      4:52      4:47 

Sucrose  added  gms.       10.00      9.79     9.50      9.37      9.155  8.94      8.73      8.21 

Wt.  of  dough  gms. 

Wt.  of  loaf  gms. 

Vol.  of  loaf  cc.  1640      1750     1750      1780      1680     1665       1610      1690 

General  Remarks:  1.5  percent  malt  flour  gave  the  largest  volume, 
finest  texture,  color  and  grain.  This  appeared  to  be  the  high  point  in 
quality,  since  all  factors  decreased  as  percentage  of  malt  flour  in- 
creased. Mean  temperature  of  fermentation  was  84°  while  that  of 
baking  was  470° F.     Time  of  baking  22  minutes. 

TABLE  XXXIX. 

The  effect  of  varying  amounts  of  malt  extract  upon  the  baking 

qualities  of  flour  1007. 


Malt  Extract  % 

Standard     .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 
Sucrose  added  gms. 
Wt.  of  dough  gms. 
Wt.  of  lt)af  gms. 
Vol.  of  loaf  cc. 

5:22      5:17 
10.00      8.94 

1640      1690 

5:12 
7.88 

1900 

5:07 
6.82 

1620 

5:02 
5.76 

1660 

4:57 
4.70 

1850 

4:52 
3.64 

1890 

4:47 
1.52 

1760 

General  Remarks :  The  use  of  3  percent  malt  extract  gives  the  best 
loaf  for  color,  texture  and  grain  and  the  best  general  appearing  loaf. 
Malt  extract  increased  the  bloom,  color  of  crumb  and  volume,  through- 
out the  bake.  Mean  temperature  of  fermentation  was  84°  while  that  of 
baking  was  470°  F.     The  time  of  baking  was  25  minutes. 

TABLE  XL. 
The  effect  of  varying  amounts  of  malt  flour  upon  the  baking  qualities 

of  flour  1008. 


Malt  Flour  % 

Standard     .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 

4:53      4:57 

4:52 

4:47 

4:42 

4:37 

4:32 

4:27 

Sucrose  added  gms. 

10.00      8.94 

7.88 

6.82 

5.76 

4.70 

3.64 

1.52 

Wt.  of  dough  gms. 

524        524 

525 

526 

630 

530 

531 

532 

Wt.  of  loaf  gms. 

450        460 

455 

460 

467 

466 

467 

464 

Vol.  of  loaf  cc. 

2160      2070 

2000 

2120 

2100 

1950 

1860 

•1885 

53 


General  Remarks :  The  color  of  the  crumb  was  affected  by  the  addi- 
tion of  malt  flour  as  those  preceeding.  Best  texture  and  grain  was 
secured  by  the  use  of  1.5  percent  malt  flour.  There  was  a  very 
marked  difference  between  those  loaves  made  with  1.5  and  2.0  percent 
in  texture  and  grain.  A  distinct  wheaty  smell  was  noticed  in  the 
loaves  having  malt  flour.  The  color  and  bloom  were  about  alike. 
Temperature  of  fermentation  was  83°  and  the  temperature  of  baking 
480°  F.     Time  of  baking  was  24  minutes. 

TABLE  XLI. 
The  effect  of  varying  amounts  of  malt  extract  upon  the  baking  quali- 
ties of  flour  1008. 


Malt  Extract  % 

Standard     .5 

1.0 

1.5 

2.0 

2.5 

3.0 

5.0 

Fermentation  Hrs. 

4:53      4:57 

4:52 

4:47 

4:42 

4:37 

4:32 

4:27 

Sucrose  added  gms. 

10.00      8.94 

7.88 

6.82 

5.76 

4.70 

3.64 

1.52 

Wt.  of  dough  gms. 

524        513 

513 

514 

518 

521 

519 

525 

Wt.  of  loaf  gms. 

450        457 

457 

454 

450 

450 

453 

460 

Vol.  of  loaf  cc. 

2160      2020 

2040 

2070 

1995 

2130 

2180 

2130 

General  Remarks :  Color  was  good  throughout  the  bake,  the  bread 
made  with  3  percent  had  the  best  grain  and  texture.  Added  malt  ex- 
tract gave  the  bread  a  slight  sweet  odor  and  taste.  Bloom  was  even 
throughout  the  whole  bake.  Temperature  of  fermentation  83°  and 
was  baked  out  in  22  minutes  at  a  temperature  of  500°  F. 

III.  DISCUSSION. 
Changes  in  pH,  Temperature,  Time  and  Concentration  and  Their  Ef- 
fects Upon  the  Activity  of  the  Diastases  Contained  in  a  Com- 
mercial Malt  Flour. 
As  already  noted  in  the  historical  review  of  the  diastase  literature, 
Sherman  and  his  co-workers  found  that  the  pH  for  the  optimum  ac- 
tivity of  diastase  of  different  origins  were  not  the  same  and  it  could 
hardly  be  expected  that  the  diastases  derived  from  different  sources  of 
barley  would  have  the  same  activity  at  the  same  hydrogen  ion  concen- 
tration. A  study  of  Table  VIII,  and  Figure  1  show  that  the  greatest 
activity  of  the  diastases,  in  the  malt  flour  used  in  this  investigation, 
was  at  a  pH  of  4.26,  while  that  found  by  Sherman  for  a  highly  purified 
malt  amylase  was  very  close  to  a  pH  of  4.4  which  shows  relatively 
close  agreement.  It  will  be  noted  in  Table  XXXI,  where  the  changes 
in  hydrogen  ion  concentration  of  fermenting  dough  was  followed,  that 
in  the  later  stages  of  fermentation  the  dough  was,  with  two  exceptions, 
at  a  pH  of  about  5.0.  Although  this  is  not  at  the  optimum  for  dias- 
tatic  activity,  it  will  be  noted  from  Figure  1  that  the  rate  of  reaction 
was  very  high  at  this  point.  This  is  of  significance  when  we  consider 
that  the  sugars  formed  in  the  later  stages  of  fermentation  are  impor- 
tant factors  in  determining  the  size  of  the  resulting  loaf. 

54 


Table  IX  and  Figure  2  show  that  the  diastatic  activity  of  the  malt 
flour  was  practically  constant  over  a  period  of  eight  hours  digestion. 
A  slight  decrease  in  activity  was  noticeable  as  time  of  digestion  pro- 
ceeds, but  for  all  practical  purposes,  the  rate  of  reaction  showed  a 
straight  line  when  the  quantity  of  dextrose  formed  was  plotted  against 
time. 

Table  X  and  Figure  3  show  that  increase  in  temperature  up  to 
65°C.  increased  the  activity  of  the  diastase.  From  27°  -  45°C.  the  rate 
of  reaction  increased  quite  regularly  with  each  increment  of  rise  in 
temperature.  Between  45°  and  50°  the  rate  was  greatly  increased, 
while  between  50°  and  60°  the  increase  was  very  rapid,  following 
quite  closely  the  Vant  Hoflf  and  LaBelle  law.  After  60°  the  increase 
in  activity  was  not  so  marked  and  the  diastatic  activity  was  apparently 
at  a  maximum  at  65 °C.,  as  a  decline  in  activity  was  noted  with  further 
increase  in  temperature.  Table  XII  shows  that  when  the  percentage 
of  malt  flour  was  increased  from  0-50  per  cent,  the  percentage  of  dex- 
trose formed  from  malt  flour  increased  from  1.63  to  6.06  percent.  This 
was  calculated  to  show  the  quantity  of  raw  starch  converted  to  dex- 
trose. The  greatest  effect  of  added  diastase  was  in  the  first  10  percent 
of  added  malt  flour,  which  gave  an  increase  in  dextrose  from  1.03  to 
3.67  percent. 
The  Effect  of  Diastatic  Enzymes  Upon  Starch  of  Different  Flours. 

The  addition  of  diastatic  ferments  to  wheat  flours  increased  the  re- 
ducing sugars,  when  digested  at  27°  C.  for  1  hour.  As  the  amount  of 
diastatic  ferment  was  increased  a  corresponding  increase  in  reducing 
sugars  was  noted.  All  of  the  flours  used  in  the  experiment  did  not 
react  in  the  same  way  to  the  addition  of  malt  flour,  as  great  differences 
were  shown  not  only  in  the  initial  amounts  of  reducing  sugars  (1 
hour  digestion  without  diastase)  contained,  but  with  an  increase  in 
malt  flour  more  starch  was  converted  in  some  flours  than  in  others. 
In  general,  but  for  one  exception,  the  weaker  flours  produce  less  re- 
ducing sugars  than  do  the  stronger,  when  digested  with  the  same 
amounts  of  malt  flour.  From  the  data  presented  in  Table  XIII  and 
Figure  5,  it  will  be  noted  that  the  commercial  wheat  starch  shows  the 
least  amount  of  initial  reducing  sugars  and  responds  less  to  the 
action  of  malt  flour  than  any  of  the  wheat  flours.  Flour  1003,  a 
decidedly  weak  Pacific  Coast  flour,  is  next  in  the  ^eries;  it  shows  a 
slightly  greater  amount  of  initial  reducing  sugars  (digestion  1  hour 
without  added  diastases)  and  responds  a  trifle  more  readily  to  conver- 
sion by  the  malt  flour,  than  does  the  wheat  starch.  The  next  flour, 
1011,  is  a  patent  milled  from  a  soft  winter  wheat  and  runs  just  a  trifle 
higher  in  initial  sugar  content  and  appears  to  be  more  easily  converted 
than  flour  1003.     These  two  flours,  and  the  wheat  starch  constitute  a 

55 


special  group  as  far  as  sugar  content  is  concerned.  While  the  wheat 
starch  has  no  baking  value,  the  other  two,  namely  1003  and  1011, 
showed  very  poor  baking  qualities. 

The  patent  flours  of  good  baking  strength  are  highest  in  the  list  of 
initial  sugar  content  and  with  one  exception  produce  under  the  action 
of  diastatic  enzymes,  more  dextrose  than  do  the  weaker  flours.  The 
exception  noted  was  flour  1008,  which  showed  the  largest  volume  in 
the  baking  test,  had  a  greater  initial  sugar  content  than  any  of  the 
other  flours,  but  did  not  produce  as  much  dextrose  as  flours  1001  and 
-i009  when  digested  with  malt  flour.  Flour  1007,  a  clear  flour  of  very 
poor  baking  qualities,  milled  from  Canadian  wheat  stood  fourth  in  the 
series  in  regard  to  initial  sugar  content.  Under  the  action  of  the  dias- 
tase in  malt  flour,  however,  the  reducing  sugars  increased  out  of  all 
proportion  to  its  baking  strength  and  on  the  addition  of  .5000  grams 
of  malt  flour,  it  contained  more  reducing  sugars  than  any  of  the  other 
flours  with  a  like  concentration  of  malt  flour. 

In  general  the  initial  sugar  content  (digestion  1  hour  without  added 
diastases)  indicated  the  baking  qualities  of  the  flour  quite  accurately. 
This  in  turn  depends  to  a  large  extent  upon  the  diastatic  enzymes  con- 
tained in  the  flour  itself.  From  the  data  presented,  it  would  seem  that 
the  starch  of  the  strong  flours  was  generally  more  easily  converted 
than  that  of  weak  flours.  This  was  not  invariable,  as  flour  1008,  a  par- 
ticularly strong  patent  flour  showed  only  a  very  slight  increase  in  sol- 
uble sugars  when  digested  with  approximately  5  percent  malt  flour, 
whereas  flour  1007,  a  clear  flour  of  notably  poor  baking  qualities, 
showed  a  phenomenal  increase  under  the  same  experimental  condi- 
tions. 

The  Production  of  Reducing  Sugars  in  the  Panary  Fermentation  of 
Bread  and  the  Effects  of  Diastases  Added  in  the  Dough. 

In  this  phase  of  the  investigation,  flours  1008  a  strong  patent,  1003  a 
weak  flour,  and  1002  a  clear  flour  of  good  baking  strength,  were  used. 
The  data  in  Tables  XIV  to  XXI  and  in  Figures  6,  7  and  8  show  how 
these  three  typical  flours  behave  with  regard  to  producing  reducing 
sugars,  when  fermented  normally  and  with  different  amounts  of  added 
malt  preparations.  In  order  to  have  a  check  on  the  reducing  sugars 
actually  produced  during  the  fermentation  period,  a  check  series  was 
run  at  the  same  time,  identical  in  all  respects  but  having  no  yeast.  In 
every  instance  where  a  diastatic  enzyme  was  added,  there  was  an 
increase  in  reducing  sugars,  over  that  of  the  normal  dough,  throughout 
the  fermentation  period. 

Flour  1008  had  by  far  the  greater  amounts  of  reducing  sugars,  when 
the  same  additions  of  malt  flour  or  malt  extract  were  made,  than  did 

56 


the  other  two  flours.  Flour  1002  was  next  and  1003  was  at  the  bot- 
tom of  the  list.  The  curves  in  Figure  6,  representing  the  production 
of  sugars  in  Flour  1008,  are  all  of  the  same  general  type,  that  is,  the 
yeast  dough  curves  are  alike  and  the  "no  yeast"  curves  are  alike.  In 
the  yeast  doughs  the  peak  of  sugar  formation  or  the  point  where  the 
diastases  were  producing  as  much  available  sugar  as  the  yeast  was  us- 
ing up,  was  at  the' first  punch  after  two  and  one-half  hours  of  fermen- 
tation. From  this  time  on  the  yeast  seems  to  be  stimulated  and  uses 
up  the  sugar  faster  than  it  is  produced,  steadily  diminishing  the  sur- 
plus that  the  diastases  have  piled  up  in  the  first  half  of  the  fermenta- 
tion period.  In  the  doughs  which  have  no  yeast,  conversion  seems  to 
be  slightly  faster  in  the  later  stages  of  fermentation  than  in  the  begin- 
ning. If  this  is  the  case  in  the  yeast  dough,  the  yeast  undoubtedly 
increases  in  activity  as  fermentation  proceeds.  When  3  percent  malt 
extract  is  used,  the  sugar  content  is  decidedly  higher  than  in  any  of 
the  other  doughs.  This  is  of  decided  advantage  as  the  yeast  has  a 
large  surplus  of  sugars  to  draw  from. 

The  curves  for  flour  1002  (Figure  8),  are  very  similar  to  those  for 
flour  1008  (Figure  6),  with  the  exception  that  sugar  production  ap- 
peared to  have  reached  a  maximum  at  the  end  of  1  hour  of  fermenta- 
tion in  the  dough  to  which  no  diastatic  enzymes  were  added  and  the 
one  to  which  3  percent  malt  extract  was  added.  The  doughs,  to  which 
1.5  and  4.0  percent  malt  flour  were  added,  reached  their  maximum  of 
sugar  production  at  the  first  punch  after  a  fermentation  period  of  2 
hours  and  fifteen  minutes.  The  amounts  of  sugars  produced  by  the 
diastatic  enzymes  are  remarkably  constant  during  the  time  of  fermen- 
tation, with  the  greatest  conversion  produced  by  the  addition  of  4  per- 
cent malt  flour.  As  in  the  preceding  series,  the  dough  to  which  the 
malt  extract  was  added  showed  a  larger  amount  of  reducing  sugars 
throughout  the  entire  fermentation  period. 

A  difference  in  the  shape  of  the  curves  is  at  once  noticed  (Figure  7) 
where  the  sugars  produced,  in  the  fermentation  of  flour  1003,  are  fol- 
lowed. Instead  of  an  initial  increase  in  reducing  sugars,  as  was  the 
case  with  the  preceding  strong  flours,  the  yeast  utiltizes  all  available 
sugars  immediately,  with  a  continued  decrease  in  sugar  content  as  fer- 
mentation proceeded.  A  slight  increase  in  reducing  sugars  was  se- 
cured by  the  use  of  4  percent  malt  flour,  which  reached  the  highest 
point  after  2  hours  fermentation.  The  addition  of  3  percent  malt 
extract  seemed  to  be  able  to  convert  enough  starch  to  hold  the  avail- 
able reducing  sugars  constant  for  one  hour,  but  after  this  time  the 
yeast  increased  in  activity  and  the  available  sugars  dropped  oflf  rap- 
idly. 

57 


From  an  inspection  of  Tables  XIV-XVI  and  XXI-XXIV,  and  Fig- 
ures 6  and  8,  it  appeared  that  an  addition  of  diastatic  enzymes  to  a 
dough  resulted  in  a  surplus  of  reducing  sugars  during  the  earlier 
stages  of  fermentation.  This  surplus  was  used  up  in  the  later  stages 
of  fermentation  along  with  the  sugars  simultaneously  produced  by  the 
diastatic  enzymes.  It  also  appeared  that  yeast  activity  was  increased 
to  a  considerable  extent  when  the  carbon  dioxide  was  punched  out 
of  the  dough  ;  at  least  it  seems  to  have  been  coincident  with  the  punch- 
ing of  the  dough  in  the  case  of  the  stronger  flours.  It  was  also  evi- 
dent from  the  amounts  of  reducing  sugars  available,  that  the  flours 
which  showed  good  baking  qualities  had  a  greater  diastatic  activity 
than  did  the  flour  of  poor  baking  strength.  The  malt  preparations 
when  added  to  weak  flours  produced  less  sugars  in  proportion  than 
when  added  to  strong  flours.  Whether  or  not  the  starch  of  the  former 
was  harder  to  hydrolyze  than  that  of  the  latter  is  problematical  but 
the  data  presented  in  section  2,  and  also  in  this  section,  might  be  taken 
as  indicating  such  a  possibility. 
Effects  of  the  Proteolytic  Enzymes,  Contained  in  Malt  Preparations, 

Upon  the  Viscosity  of  Strong  and  Weak  Flours  Following  the 

Addition  of  Various  Amounts  of  N/1  Lactic  Acid. 

A  very  decided  difference  in  the  viscosity  of  a  flour-water  suspension 
was  noted  when  a  flour  was  digested,  with  and  without  malt  flour,  for 
different  periods  of  time,  as  shown  in  Table  XXV,  and  illustrated 
graphically  in  Figure  9.  The  higher  the  concentration  of  malt  flour 
added,  the  lower  was  the  resulting  viscosity  reading,  and  when  diges- 
tion was  carried  out  for  varied  lengths  of  time,  a  steady  decrease  in 
viscosity  occurred  as  time  of  digestion  progressed.  This  was  very 
noticeable  as  the  percentage  of  malt  flour  was  increased. 

When  flours  of  different  baking  strengths  were  digested  with  in- 
creasing amounts  of  malt  flour  and  malt  extract,  the  viscosity  of  their 
suspensions  in  water  (plus  lactic  acid)  decreased  quite  decidedly  as 
shown  in  Tables  XXVI  and  XXVII,  and  graphically  in  Figures  10  and 
lOA.  The  strongest  flours  grouped  themselves,  and  their  suspen- 
sions in  acidified  water  have  a  much  higher  viscosity  than  those  of 
the  medium  or  weak  flours,  and  when  treated  with  4  percent  of  malt 
flour  or  malt  extract  the  strength  of  the  flours  was  indicated  by  its 
position  on  the  curve.  The  malt  extract  used  did  not  decrease  the  viscosity 
as  much  as  a  like  concentration  of  malt  flour,  and  the  conclusion  was 
that  it  did  not  contain  as  large  an  amount  of  proteolytic  enzymes  as 
did  the  malt  flour.  It  might  be  expected  that  the  stronger  flours 
would  not  show  as  great  a  decrease  in  viscosity  as  the  weak  flours. 
When  digested  with  4  per  cent  malt  flour  or  malt  extract  over  the 
range  given  in  Tables  XXVI  and  XXVII,  but  the  opposite  seems  to  be 

58 


actually  the  case.  Flour  1008,  the  strongest  flour  in  the  series,  showed 
a  decrease  in  viscosity  of  49°  MacMichael,  when  digested  with  4  per- 
cent extract,  while  the  decrease  found  for  flour  1003  under  the  same 
conditions  is  22°  and  24°  M.  respectively.  Clear  flour  1007  is  interme- 
diate in  this  particular  and  showed  a  decrease  of  36°  MacMichael, 
when  digested  with  4  percent  malt  flour. 

Although  it  has  been  demonstrated  that  salts  have  a  profound  in- 
fluence upon  the  viscosity  of  flour-water  suspensions,  the  results  in 
Table  XXVIII  show  that  while  the  viscosity  readings  were  very  much 
higher  in  a  flour-water  suspension,  from  which  the  salts  have  been 
washed  out,  the  same  relative  values  hold,  and  the  results  recorded 
above  were  not  vitiated  by  the  electrolyte  content  of  the  flours.  This 
has  been  demonstrated  in  another  way  where  a  flour  was  digested 
alone  for  four  hours,  with  4  percent  malt  flour  for  four  hours,  and  an- 
other sample  digested  alone  for  three  and  one-half  hours  and  at  the  end 
of  this  time  4  percent  malt  flour  was  added  and  digested  thirty  min- 
utes longer.  It  was  thought  that  the  salts  of  the  added  malt  flour 
would  be  extracted  in  thirty  minutes  and  would  exert  their  maximum 
effect  in  depressing  the  viscosity.  Also,  that  in  this  length  of  time 
only  a  small  amount  of  proteolytic  activity  would  take  place,  thus 
showing  a  difference  in  viscosity  between  the  flour  which  was  digested 
four  hours  with  4  percent  malt  flour  and  the  other  which  was  digested 
three  and  one-half  hours  alone,  and  thirty  minutes  with  4  percent  malt 
flour.  These  expectations  were  justified,  as  demonstrated  in  Table 
XXIX,  where  the  flour  digested  alone  gaves  a  reading  of  145°M.,  and 
that  digested  with  4  percent  malt  flour  for  four  hours  gave  a  reading 
of  81  °M.,  while  that  digested  alone  for  three  and  one-half  hours  and 
then  thirty  minutes  more  with  malt  flour  gave  a  reading  of  127° M. 
These  data  show  that  the  increase  in  viscosity  was  not  due  entirely  to 
the  electrolytes  but  to  the  partial  disintegration  of  the  protein. 

From  the  data  presented  in  Tables  XXVI  and  XXVII  it  has  been 
shown  that,  suspensions  of  strong  flours  in  water  have  a  higher  viscos- 
ity than  weak  flours  when  digested  with  and  without  added  malt  prep- 
arations. It  has  also  been  shown  that  suspensions  of  strong  flours  in 
water  show  a  greater  decrease  in  viscosity  than  do  similar  suspensions 
of  weak  flours  when  digested  with  malt  preparations  and  that  the  de- 
creases in  viscosity  recorded  above  were  not  due  entirely  to  the  elec- 
trolyte content  of  the  flours  but  to  the  cleavage  of  the  gluten,  thus  de- 
creasing its  imbibitional  capacity  and  consequently  its  viscosity. 
The  Gas  Producing  Capacities  of  Strong  and  Weak  Flours  and  the 
Effect  of  Added  Malt  Extract  Upon  Them. 

Wood  has  shown  that  the  gas  produced  by  a  flour,  especially  in  the 
later  stages  of  fermentation,  was  a  factor  in  strength,  while  Baker  and 

59 


Hulton  have  shown  that  in  some  cases  a  weak  flour  produces  as  much, 
and  in  some  cases  even  more,  gas  than  does  a  strong  flour.  They  be- 
lieved that  weak  flours  were  deficient  in  liquifying  enzymes  and  that 
an  addition  of  liquifying  enzymes  would  increase  the  gas  production 
of  a  weak  flour  to  a  considerable  extent,  while  they  would  have  little 
or  no  effect  upon  a  strong  flour.  The  data  in  Table  XXX  supports 
their  theory  and  shows  that  flours  1008  and  1009,  which  showed  very 
good  baking  qualities,  did  not  increase  to  any  extent  in  gas  producing 
capacity  when  malt  extract  was  added,  while  flour  1002,  a  strong  clear 
flour  increased  only  9  cc.  under  the  same  conditions,  and  1007,  a  clear 
flour  of  poor  baking  quality  increased  37  cc.  under  the  same  treatment. 
The  test  seems  to  be  conclusive  by  the  increase  shown  by  flour  1003, 
a  notably  weak  flour,  which  increased  80  cc.  when  1  percent  malt  ex- 
tract was  added. 

The  Changes  in  Hydrogen  Ion  Concentration  Taking  Place  During 
the  Fermentation  of  the  Dough. 

The  changes  in  hydrogen  ion  concentration  taking  place  during  the 
fermentation  of  the  dough,  are  recorded  in  Table  XXXI  and  show  that 
steady  increase  in  hydorgen  ion  concentration  takes  place  as  fermen- 
tation proceeds.  With  two  exceptions  the  doughs  when  ready  for  the 
oven  had  a  hydrogen  ion  concentration  of  approximately  pH  5.  The 
two  flours  which  had  a  higher  pH  were  clear  flours  of  very  poor 
baking  strength. 

The  Effects  of  Malt  Flour  and  Malt  Extract  Upon  the  Baking  Value 

of  Flour. 

In  flour  1001,  a  strong  patent  flour,  the  volume  was  considerably 
increased  by  the  use  of  2.5  percent  malt  flour.  This  advantage  was 
materially  offset  by  the  decrease  in  color.  With  the  use  of  the  malt  ex- 
tract, the  volume  increased  with  additions  up  to  3  percent  with  not 
much  decrease  in  color,  while  a  sweet  honey-like  flavor  is  evident 
which  adds  to  the  value  of  the  loaf.  The  data  in  Table  XXXIII 
shows  that  the  baking  qualities  of  the  flour  were  improved  when  3  per- 
cent malt  extract  was  used. 

Flour  1002,  a  fairly  strong  clear  flour,  increased  in  volume  with  the 
addition  of  malt  flour.  The  greatest  volume  was  secured  by  the  use 
of  2  percent  malt  flour  for  the  weight  of  the  dough  baked  out.  While 
the  grain  and  texture  were  uniform  throughout,  the  decrease  in  color 
value  offset  the  advantages  secured  by  the  increase  in  volume.  In 
using  malt  extract  the  greatest  volume  was  secured  by  the  use  of  1.5 
and  2.0  percent,  and  decidedly  the  best  loaves  were  thus  produced, 
since  texture  and  grain  increased  in  fineness  as  the  amount  of  malt  ex- 
tract increased.     The  slight  decrease  in  color  value  was  not  a  serious 

60 


objection  and  the  addition  of  1.5  to  2.0  percent  malt  extract  had  a 
decided  beneficial  effect  upon  the  baking  qualities  of  flour  1002 

With  the  use  of  1.5  percent  malt  flour  the  largest  volume  was  se- 
cured in  baking  flour  1003.  As  the  grain  was  coarse  and  the  color  off, 
however,  the  advantages  gained  by  the  increase  in  volume  were  off- 
set. A  decided  increase  in  volume  and  grain  was  secured  by  the  use 
of  1.5  percent  malt  extract  in  this  weak  flour  in  my  opinion,  the  baking 
quality  of  this  flour  was  thus  greatly  increased. 

In  clear  flour  1007,  the  use  of  1.5  percent  malt  flour  increased  the 
volume  as  well  as  the  texture  and  grain,  and  in  this  flour  the  addition 
of  malt  flour  was  beneficial.  The  use  of  3  percent  malt  extract  gave  a 
decided  improvement  in  the  baking  qualities  of  flour  1007  as  far  as 
volume,  grain,  texture  and  color  is  concerned. 

In  flour  1008,  the  strongest  flour  of  the  series,  the  use  of  1.5  percent 
malt  flour  improved  the  texture  and  grain  but  darkened  the  color  con- 
siderably. The  use  of  malt  flour  did  not  increase  the  baking  qualities 
of  this  flour,  while  on  the  other  hand  the  use  of  3  percent  malt  extract 
increased  the  volume  slightly,  improved  the  texture  and  grain  thus 
improving  the  baking  qualities  to  a  marked  extent. 


61 


IV.  SUMMARY 

This  paper  deals  with  the  effects  of  diastatic  ferments  upon  the 
strength  of  wheat  flours.  Tables  and  graphs  have  been  presented, 
showing: 

1.  Optimum  temiperature  for  the  diastatic  activity  of  the  malt  flour 
used  was  at  temperature  of  65  °C. 

2.  Optimum  hydrogen  ion  concentration  for  the  diastatic  enzymes 
in  malt  flour  was  at  a  pH  of  4.26. 

3.  Constant  diastatic  activity  was  shown  by  the  malt  flour  over  a 
period  of  eight  hours  when  digested  at  27° C. 

4.  Concentrations  of  added  diastase  exert  their  greatest  effect  in 
the  first  10  percent  of  added  malt  flour,  giving  an  increase  in  dextrose 
from  1.63  to  3.67  percent. 

5.  Diastatic  ferments  when  added  to  wheat  flours  increase  the 
reducing  sugars,  when  digested  at  27° C  for  1  hour.  The  strong 
flours  showed  a  higher  sugar  content  and  greater  diastatic  activity 
than  did  the  weaker  flours.  The  starch  of  the  strong  flours  appeared 
to  be  more  easily  hydrolyzed  by  diastatic  ferments  than  that  of  the 
weaker  flours. 

6.  Addition  of  diastatic  ferments  to  a  dough  convert  the  starch 
to  reducing  sugars  and  in  the  earlier  stages  of  fermentation,  produce 
a  surplus  of  fermentable  sugars  in  the  doughs  made  from  strong 
flours.  This  surplus  soon  disappears  as  the  activity  of  the  yeast 
increases,  and  at  the  end  of  the  fermentation  period  the  dough  is 
nearly  depleted  of  available  sugars. 

7.  Suspensions  of  strong  flours  in  water  had  a  higher  viscosity  (on 
the  addition  of  lactic  acid)  than  similar  suspensions  of  weak  flours 
when  incubated  alone  or  with  added  diastatic  ferments  in  the  form 
of  malt  flour  and  malt  extract.  The  course  of  proteolytic  activity 
could  be  accurately  followed  by  the  change  in  viscosity  when  wheat 
flour  was  digested  with  added  malt  flour.  The  presence  of  naturally 
occurring  salts  of  the  w^heat  flours  did  not  vitiate  the  viscosity  readings. 

8.  Gas  producing  capacity  of  weak  flours  was  greatly  increased 
when  fermented  with  added  malt  extract.  This  was  not  the  case 
when  strong  flours  were  fermented  with  added  malt  extract. 

9.  Hydrogen  ion  concentration  of  the  dough  steadily  increased  as 
fermentation  proceeded.  With  two  exceptions,  the  doughs  were  at 
approximately  a  pH  of  5.0  when  ready  for  the  oven. 

10.  Addition  of  malt  flour  and  malt  extract  to  doughs  increased 
the  volume  of  the  resulting  bread.  In  all  cases  the  use  of  malt  extract 
gave  a  superior  loaf  of  bread  in  volume,  grain  and  texture,  thus 
increasing  the  baking  strength  of  the  flours. 

62 


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n 


BIOGRAPHICAL. 

Ferdinand  Albert  Collatz  was  born  in  Duluth,  Minnesota.  He 
graduated  from  the  Duluth  Central  High  School  in  June,  1914,  and 
entered  the  University  of  Minnesota  the  same  fall,  where  he  received 
the  degree  of  Bachelor  of  Science  in  June,  1918.  Shortly  after  this 
he  entered  the  Army  and  was  assigned  to  the  Physiological  Labora- 
tory at  the  Lakeside  Hospital,  Cleveland,  Ohio,  under  the  direction 
of  Major  Roy  G.  Pierce.  During  1919-1920,  he  held  the  position  of 
Assistant  in  Agricultural  Biochemistry,  University  of  Minnesota, 
and  in  June,  1920,  received  the  degree  of  Master  of  Science  from  this 
department.  During  1920-21  he  held  the  American  Institute  of  Bak- 
ing Research  Fellowship,  where  the  experimental  work  in  this  Thesis 
was  done,  at  the  same  time  continuing  his  graduate  work  in  the  de- 
partment of  Agricultural  Biochemistry,  University  of  Minnesota. 
Here  he  studied  for  the  degree  of  Doctor  of  Philosophy. 

Major  subject.  Biochemistry. 

Minor  subject,  Botany. 

Member  of  Sigma  Xi,  Phi  Lambda  Upsilon,  Gamma  Sigma  Delta, 
Gamma  Alpha;  Member  of  the  American  Chemical  Society. 


73 


Makers 
Syracuse,  N.  Y. 

PAT.  JAH  21,  1908 


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